Arginine Group Research Articles

Meaning and consequence of the coexistence of competitive hydrogen bond/salt forms on the dissociation orientation of non-covalent complexes.

Non-covalent complexes (NCC) between hexose monophosphates (HexP) and arginine (R) were analyzed using ESI MS and MS/MS in negative mode under different (hard, HC and soft, SC) desolvation conditions. High resolution mass spectrometry (HRMS) revealed the presence of different ionic species, namely, homo- and heteromultimers of R and HexP. Deprotonated heterodimers and corresponding sodiated species were enhanced under HC likely due to a decrease in available charge number associated with the reduction of H+/Na+ exchange. The quantum calculations showed that the formation of covalent systems is very little exothermic, therefore, such systems are disfavored. Desolvation dependent CID spectra of deprotonated [(HexP+R)‒H]- complexes demonstrated that they can exist within the hydrogen bond (HB) and salt bridge (SB) forms, yielding either NCC separation or covalent bond cleavages, respectively. Although HB forms are the main species, they cannot survive under HC; therefore, the minor SB forms became detectable. Energy-resolved mass spectrometry (ERMS) experiments revealed diagnostic fragment ions from both SB and HB forms, providing evidence that these isomeric forms are inconvertible. SB formation should result from the ionic interactions of highly acidic group of HexP with strongly basic guanidine group of arginine and thus requires an arginine zwitterion (ZW) form. This was confirmed by quantum calculations. Ion-ion interactions are significantly affected by the presence of sodium cation as demonstrated by the fragmentation patterns of sodiated complex species. Regarding CID data, only SB between protonated amino group of R and deprotonated phosphate group of HexP could be suggested, but the primary amine is not enough basic then, the SB must be fleeting. Nevertheless, the observation of the covalent bond cleavages suggests the presence of structures with a free negative charge able to induce fragmentations. Indeed, according to quantum calculations, solvated salt (SS) systems involving Na+/COO- salt solvated by neutral phosphate and negative charge on sugar ring are preferentially formed.

Remineralization of early enamel caries lesions using different bioactive elements containing toothpastes: An in vitro study.

Demineralization can be arrested or reversed when remineralization agents are applied to incipient carious or non-cavitated carious lesions. A large number of therapeutic agents including non-fluoridated products have been developed to promote enamel remineralization. This study aims to evaluate the efficacy of different bioactive elements containing toothpastes in remineralization of artificial enamel lesions. Artificial carious lesions were created on 40 human enamel slabs, and were randomly divided into four groups: (1) control group (no treatment), (2) casein phosphopeptide-amorphous calcium phosphate group (CPP-ACP, GC Tooth Mousse), (3) 8% arginine and calcium carbonate group (ACC, Colgate Sensitive Pro-Relief), (4) calcium sodium phosphosilicate group (CSP, NovaMin®). All samples were subjected to 15 days of pH-cycling. Subsequently, a one-hour acid resistance test was carried out. Surface hardness of the samples was assessed using the Knoop hardness test, and surface morphology and roughness were assessed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed using one-way ANOVA, Tukey's test and paired t test. The three tested toothpastes exhibited a significantly higher remineralization efficacy compared with the control group (P< 0.05 for all). After pH-cycling, the specimens treated with Colgate Sensitive Pro-Relief and NovaMin® showed a significant higher surface hardness (P< 0.001 and P= 0.03, respectively) and lower surface roughness (P< 0.05 for both) compared those treated with GC Tooth Mousse. While after the acid resistance test, all groups showed a significant loss of surface hardness (P< 0.001 for all) and significant increase of surface roughness (P< 0.05). The specimens treated with Colgate Sensitive Pro-Relief and NovaMin® still showed a significant higher surface hardness and lower surface roughness in comparison with those treated with GC Tooth Mousse (P< 0.05 for all). No significant difference was found in surface hardness and roughness between Colgate Sensitive Pro-Relief and NovaMin® during the pH-cycling test and acid resistance test (P= 0.45 and P= 0.83, respectively). Colgate Sensitive Pro-Relief and NovaMin® present an advantage in enhancing remineralization and inhibiting demineralization for early enamel carious lesions in comparison with GC Tooth Mousse.

Purification and characterization of a novel heterodimer protease inhibitor from Streptomyces spp. VL J2 with potential biopesticidal activity against H. armigera

A protease inhibitor (PI) was isolated and purified from halo-alkaliphilic Streptomyces spp. VL J2. SDS-PAGE of purified PI revealed it to be a heterodimer of two unidentical subunits of 27.5 and 11.08kDa, which corroborates well with intact molecular mass of 38.5kDa obtained by GPC and MALDI −TOF. Inhibitory activity was confirmed by activity staining and reverse zymogram studies and the inhibitor was found to retain activity at <50°C and pH 2–9.5. It showed presence of two isoforms with isoelectric point of 5.5 and 5.7. The inhibition of trypsin and chymotrypsin indicated it to be a serine protease type belonging to serpin family. The stoichiometry of trypsin-inhibitor interaction was 1:2. Modification of amino acid showed presence of arginine and free sulfhydryl group at active site. Kinetic studies revealed the non-competitive type of inhibition of trypsin with low Ki value (9.4×10−9M). Activity against H. armigera showed significant decline and delay in larval (51%), pupal weights and periods, respectively, prominent physical abnormalities and reduced nutritional indices as a function of treatment. The results suggest that the purified PI has promising pesticidal activity and could serve as a potential candidate gene for transgenic plant research.

THE DIRHENIUM(III) COMPLEX COMPOUND WITH ARGININE

Complex compounds of dirhenium(III), containing an unique quadruple metal-metal bond with low toxicity have a number of useful biological properties, such as antitumoral, antihemolytic, antiradical, hepato- and nephroprotective that stimulates the expansion of the range of such compounds due to the diversity of the ligand sphere. The method of synthesis of the dirhenium(III) complex compound with arginine was elaborated. For obtaining the target product the reaction of (NBu4)2Re2Cl8 with arginine in a molar ratio of 1:10 in an inert atmosphere was carried out. A mixture of polar organic solvents (acetone – acetonitrile in the ratio 4:1) was used. Obtained substance was recrystallized from ethyl acetate. The yield of product was 43%. The compound has a blue color, soluble in polar organic solvents and water. Composition and structure of the obtained cluster compound cis-[Re2(Arg)2Cl4ˑ2CH3CN]Cl2 were confirmed by elemental analysis, electronic absorption (EAS) and IR spectroscopy, molar electric conductivity. In the visible region of the EAS shift of the absorption band with 14700 cm –1 to 16670 cm –1 was observed. New position of the absorption band corresponds to d→d* electronic transition on d component of quadruple Re-Re bond and characterized complexes with cis-position of bridging carboxylates ligands to the cluster Re2 6+. In the IR spectra intense band characteristic of uncoordinated CO-group in the arginine absent and there vibrations at 1471 cm-1, which points to bridging coordination of carboxyl groups to the cluster Re2 6+. Protonation of amine group which situated near α-C atom can prove through bands at 1623 cm-1 δas(NH3 +), 1495 cm-1 δs(NH3 +). The presence in the spectral picture bands at 2875 cm-1, 1665 cm-1, and 740 cm-1 confirms the storage the guanidinium group in an uncoordinated state. It is shown, that is realized a bridging coordination of carboxyl group of arginine to the cluster Re2 6+ with coordination of two ligands of amino acids to cis-position.

Arginine modified polymeric micelles as a novel drug delivery system with enhanced endocytosis efficiency

A new drug delivery system with improved endocytosis efficiency based on arginine modified poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL) diblock copolymers was developed successfully. The structures of amphiphilic copolymers were verified by proton Nuclear Magnetic Resonance (1H NMR), Fourier Transform Infrared (FTIR) and Gel Permeation Chromatography (GPC). The amphiphilic copolymers could self-assemble into spherical micelles with critical micelle concentration (CMC) at approximately 0.03mg/mL. Biocompatibility, cellular internalization efficiency and in vitro antitumor effect of the polymeric micelles were studied. Results showed that drug-free micelles were nontoxic to cells. The Confocal Laser Microscopy (CLSM) and the flow cytometry as well as the antitumor activity tests all revealed that drug-loaded micelles modified by arginine groups (guanidino) exhibited higher endocytosis efficiency than those without modification, resulting in a lower IC50 value to kill tumor cells and meanwhile averting the “competitive binding” problem. Also, in vivo results demonstrated that arginine modified polymeric micelles could deliver the drug to tumor site more efficiently than ones without any modification, thus indicating guanidino in polymeric micelles could benefit the internalization of micelles to fully exert the function of killing tumors. In general, guanidinylation strategy in this splendid novel micelle system has a great potential to improve the therapeutic effect of nanoparticle-based drug delivery system for cancer therapy in the future.

A novel procedure for the assessment of the antioxidant capacity of food components

Carbonylation, an oxidative modification of the amino group of arginine and lysine residues caused by reactive oxygen species, has emerged as a new type of oxidative damage. Protein carbonylation has been shown to exert adverse effects on various protein functions. Recently, the role of food components in the attenuation of oxidative stress has been the focus of many studies. Most of these studies focused on the chemical properties of food components. However, it is also important to determine their effects on protein functions via post-translational modifications. In this study, we developed a novel procedure for evaluating the antioxidant capacity of food components. Hydrogen peroxide (H2O2)-induced protein carbonylation in HL-60 cells was quantitatively analyzed by using fluorescent dyes (Cy5–hydrazide dye and IC3–OSu dye), followed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and fluorescence determination. Among a panel of food components tested, quinic acid, kaempferol, saponin, squalene, trigonelline, and mangiferin were shown to be capable of suppressing protein carbonylation in HL-60 cells. Our results demonstrated that this fluorescence labeling/SDS–PAGE procedure allows for the detection of oxidative stress-induced protein carbonylation with high sensitivity and quantitative accuracy. This method should be useful for the screening of new antioxidant food components as well as the analysis of their suppression mechanism.

Arginine, N-carbamylglutamate, and glutamine exert protective effects against oxidative stress in rat intestine.

The objective of the current study is to evaluate the effects of dietary supplementation with arginine (ARG), N-carbamylglutamate (NCG), and glutamine (GLN) on rat intestinal morphology and antioxidant status under oxidative stress. Rats were fed for 30 d with one of the following iso-nitrogenous diets: basal diet (BD), BD plus 1% ARG, BD plus 0.1% NCG, and BD plus 1% GLN. On day 28, half of the rats fed BD were intraperitoneally injected with 12 mg/kg body weight of diquat (DT; i.e., the DT group) and the other half was intraperitoneally injected with sterile solution (i.e., the control group). The other diet groups were intraperitoneally injected with 12 mg/kg body weight of DT (i.e., DT + 1% GLN [DT + GLN], DT + 1% ARG [DT + ARG], and DT + 0.1% NCG [DT + NCG]). Rat jejunum samples obtained at 48 h after DT injection were analyzed. Results showed that DT significantly decreased catalase (CAT) activity and glutathione (GSH) content by 58.25% and 56.57%, respectively, and elevated malondialdehyde (MDA) content and crypt depth (CD) by 19.39% and 22.13%, respectively, in the jejunum (P < 0.05, relative to the control group). Compared with the DT group, the DT + GLN group exhibited significantly improved villus height (VH), villus width (VW), villus surface area (VSA), CD and total antioxidant capacity (T-AOC) activity (P < 0.05); the DT + ARG group exhibited significantly increased the ratio of VH to CD (H:D) and T-AOC activity (P < 0.05); the DT + GLN, DT + ARG and DT + NCG groups exhibited significantly enhanced CAT activity and GSH content as well as decreased MDA content (P < 0.05). Moreover, VH, VW, VSA, CD and GSH content in the DT + GLN group were higher whereas MDA content was lower compared with the corresponding values observed in both the DT + ARG and the DT + NCG groups (P < 0.05). The H:D ratio in the DT + ARG group significantly increased compared with that in the DT + NCG and DT + GLN groups (P < 0.05). Collectively, this study suggested that dietary supplementation with 1% GLN, 0.1% NCG, and 1% ARG was effective in enhancing the antioxidant status and maintaining the morphological structure of rat jejunum under oxidative stress; of these supplements, 1% GLN exerted the greatest effects on mitigating oxidative stress.

Effect of L-arginine and L-name on lysosomal cysteine proteases activity and lysosomal membranes permeability in rat aorta

Aim. To study the effect of L-arginine and its analogue N-nitro-L-arginine methyl ester (L-NAME) alone and in combination on lysosomal cysteine proteolysis and lysosomal membranes state in rat aorta.Methods. The study was performed on male Wistar rats kept under standard vivarium conditions and divided into three control and three experimental groups of 8 animals each. The experimental samples included groups with L-arginine and/or L-NAME administration. The indicators were studied in the rat aorta homogenate precipitating and non precipitating fractions. Acid phosphatase activity was determined by a standardized method of «end point», the cathepsins B, L and H activity was studied by spectrofluorimetric method.Results. When simulating the changes of nitric oxide synthesis level using L-arginine, the increase of the total cathepsins activity was detected, acid phosphatase lability coefficient was reduced, what is characterized by general lysosomal membranes stabilization. L-NAME group, in contrast, is characterized by a decrease in the cathepsin B and H activity indicators, differences from arginine group were observed in the cathepsin H in lysosomal and general fractions, lysosomal membrane is labile. Combined drugs administration reduces the total cathepsins activity, while there is an increase of the acid phosphatase total activity, all indicators suggest lysosomal membranes labilization.Conclusion. L-arginine at a dose of 500 mg/kg causes increase in the total cathepsins B, L and H activity in rat aorta due to lysosomal fraction; L-arginine action leads to lysosomal membranes stabilization; L-NAME group in cathepsin H shows a decrease in the cathepsins secretion level with decreased total activity due to both factions; combined administration of arginine + L-NAME group in cathepsin B is characterized by an increase in secretion due to lysosomes membrane labilization.

Arginine and Aerobic Training Prevent Impairment in Endothelial Function in Rats Under High Risk to Develop Metabolic Syndrome

It is not elucidated if aerobic training and arginine supplementation can have similar protective effects in individuals with constant exposure to the triggering agent of the metabolic syndrome, with the presence of subclinical alterations, but without the presence of cardiovascular disease. So the purpose of this study was to investigate the effect of arginine supplementation and aerobic training on vascular reactivity of rats under high risk of metabolic syndrome development. Wistar rats, males, adults were, initially, divided in two groups Control group (C; drinking water) and Fructose group (F; water with 10% fructose), after two weeks the F group was divided into four others groups: Fructose group (F), that continued with the same treatment, Fructose Arginine group (FA), Fructose Training group (FT) and Fructose Training Arginine group (FTA) same as F group, adding aerobic training on a treadmill and/or arginine supplementation by gavage (800mg/kg BM/day), in the last 8 weeks. There were no differences in body mass gain and caloric intake between groups (P&gt;0.05). It was observed higher serum insulin in F group compared to control group after two (P=0.046) and ten weeks (P=0.014), while it was not observed any difference between the other groups compared to C group. In relation to serum triacylglycerol levels, after two weeks, there was no difference (P=0.154) between C and F groups. After ten weeks the F group presented higher triacylglycerol concentration (P&lt;0.01) compared to C group and the training normalized this increased, however arginine supplementation had no effect on this parameter. The malondialdehyde serum concentration, an oxidative stress marked, had the same pattern as the triacylglycerol. Concerning vascular reactivity, there was no difference after two weeks of treatment. While at the end of protocol, the F group exhibited increased vasoconstrictory reactivity (P&lt;0.01) to phenylephrine when compared to C and to trained groups (FT and FTA). The F group also presented an impaired endothelial vasodilator response to acetylcholine compared to other groups and the arginine supplementation and the aerobic training were able to prevent this impaired response. Thus aerobic training prevents the metabolic alterations, the hypereactivity to phenylephrine and the endothelial damage of rats with high risk to develop metabolic syndrome, while arginine supplementation was capable only to prevent the endothelial damage in this experimental model, with no potentiating effect.Support or Funding InformationCAPES, CNPq, FAPERJ e FINEP.

Dissecting Electrostatic Contributions to Folding and Self-Assembly Using Designed Multicomponent Peptide Systems.

We investigate formation of nano- to microscale peptide fibers and sheets where assembly requires association of two distinct collagen mimetic peptides (CMPs). The multicomponent nature of these designs allows the decoupling of amino acid contributions to peptide folding versus higher-order assembly. While both arginine and lysine containing CMP sequences can favor triple-helix folding, only arginine promotes rapid supramolecular assembly in each of the three two-component systems examined. Unlike lysine, the polyvalent guanidyl group of arginine is capable of both intra- and intermolecular contacts, promoting assembly. This is consistent with the supramolecular diversity of CMP morphologies observed throughout the literature. It also connects CMP self-assembly with a broad range of biomolecular interaction phenomena, providing general principles for modeling and design.

Dietary arginine and N-carbamylglutamate supplementation enhances the antioxidant statuses of the liver and plasma against oxidative stress in rats.

N-Carbamylglutamate (NCG), an effective precursor of arginine (ARG), can enhance ARG synthesis, increase intestinal growth, and improve reproductive performance. However, the antioxidant effect of NCG remains largely unknown. This study aims to survey the effects of ARG and NCG supplementation on the antioxidant statuses of the liver and plasma in rats under oxidative stress. Rats were fed for 30 days with one of the three iso-nitrogenous diets: basal diet (BD), BD plus 1% ARG, and BD plus 0.1% NCG. On day 28, half of the rats fed with BD were intraperitoneally injected with 12 mg per kg body weight of diquat (diquat group) and the other half was injected intraperitoneally with sterile 0.9% NaCl solution (control group). The other diet groups also received an intraperitoneal injection of 12 mg per kg body weight of diquat, as follows: diquat + 1% ARG (DT + ARG), and diquat + 0.1% NCG (DT + NCG). Rat liver and plasma samples obtained 48 h after diquat injection were analyzed. Results indicated that diquat significantly affected the plasma conventional biochemical components (relative to the controls), which were partially alleviated in both the DT + ARG and DT + NCG groups (P < 0.05). Diquat also significantly decreased the glutathione (GSH) content (by 30.0%), and decreased anti-superoxide anion (ASA; by 13.8%) and anti-hydroxyl radical (AHR; by 38.9%) abilities in the plasma, and also decreased catalase (CAT) activity both in the liver (by 17.5%) and plasma (by 33.4%) compared with the control group. By contrast, diquat increased the malondialdehyde (MDA) content (by 23.0%) in the plasma (P < 0.05) compared with the control group. Relative to those of the diquat group, higher CAT activity and GSH content were noted in the plasma of the DT + ARG group and in the liver of both DT + ARG and DT + NCG groups (P < 0.05). Furthermore, the DT + ARG group exhibited significantly enhanced plasma ASA activity (P < 0.05). The DT + NCG group showed significantly improved total antioxidant capacity (T-AOC) in the liver and plasma (P < 0.05). Increased GSH content and elevated ASA and AHR activities were also found, but the MDA content in the plasma was depleted (P < 0.05). Compared with the DT + ARG group, the DT + NCG group showed increased liver and plasma T-AOC, enhanced plasma AHR activity, increased liver ASA activity, and decreased plasma MDA content (P < 0.05). Overall, supplementation of 1% ARG and 0.1% NCG can partially protect the liver and plasma from oxidative stress. Furthermore, compared with 1% ARG, 0.1% NCG more effectively alleviated oxidative stress.

Role of arginine and lysine in the antimicrobial mechanism of histone-derived antimicrobial peptides

Translocation of cell-penetrating peptides is often promoted by increased content of arginine or other guanidinium groups. However, relatively little research has considered the role of these functional groups on antimicrobial peptide activity. This study compared the activity of three histone-derived antimicrobial peptides—buforin II, DesHDAP1, and parasin—with variants that contain only lysine or arginine cationic residues. These peptides operate via different mechanisms as parasin causes membrane permeabilization while buforin II and DesHDAP1 translocate into bacteria. For all peptides, antibacterial activity increased with increased arginine content. Higher arginine content increased permeabilization for parasin while it improved translocation for buforin II and DesHDAP1. These observations provide insight into the relative importance of arginine and lysine in these antimicrobial peptides.

Effects of arginine supplementation during early gestation (day 1 to 30) on litter size and plasma metabolites in gilts and sows.

Two experiments were conducted, under typical commercial swine production conditions, to determine effects of dietary arginine supplementation during early gestation on the performance of gilts and sows. In Exp. 1, between d 1 and 30 of gestation, 62 Landrace gilts and 113 sows consumed a corn- and soybean meal-based diet supplemented with 1.3% -arginine HCl or 2.2% -alanine. Total numbers of piglets born ( < 0.05) and born alive ( < 0.01) per litter and litter birth weights of piglets born ( < 0.05) and born alive ( < 0.05) were increased in the arginine group compared with the control. In Exp. 2, 155 multiparous Landrace sows received 1.3% -arginine HCl supplementation between d 1 and 14 (T2; = 41), d 15 and 30 (T3; = 40), or d 1 and 30 (T4; = 37), whereas the control group received 2.2% -alanine supplementation between d 1 and 30 (T1; = 37). Blood samples were randomly obtained from 6 sows per group on d 1, 14, and 28 of gestation to determine plasma concentrations of AA and related metabolites. Total numbers of piglets born ( = 0.084) and born alive ( = 0.080) per litter tended to be higher for sows supplemented with arginine between d 1 and 14 of gestation (T2) than for control sows (T1). Concentrations of arginine and nitric oxide metabolites were greater ( < 0.05) in T4 compared with T1 and T3 on d 14 of gestation and were also greater in T4 compared with T1 and T2 on d 28 of gestation. Plasma concentrations of spermidine ( < 0.001) were increased in T3 and T4 compared with T1 and T2 on d 28. These results indicate that dietary arginine supplementation during early gestation improves the reproductive performance of gilts and sows, possibly via nitric oxide and polyamine-dependent mechanisms.

Determination of Reduced Nicotinamide Adenine Dinucleotide with a Protamine Multiwalled Carbon Nanotube Electrode

ABSTRACTA bionanocomposite prepared from multiwalled carbon nanotubes and protamine sulfate is reported for the electrocatalytic determination of dihydronicotinamide adenine dinucleotide. Protamine sulfate was adsorbed via π-π interactions and hydrogen bonds between protonated amines on arginine and surface groups on the multiwalled carbon nanotubes. The multiwalled carbon nanotube protamine composite accumulated dihydronicotinamide adenine dinucleotide on the electrode surface, resulting in high sensitivity and a low limit of detection for dihydronicotinamide adenine dinucleotide. The nanocomposite was employed for dehydrogenase-based biosensing. Alcohol dehydrogenase was allowed to adsorb on the bionanocomposite surface and the sensitivity of the resulting electrode to ethanol was measured. The alcohol biosensor had an excellent sensitivity of 738.5 µA/mM with a low limit of detection of 50 nM.

Effects of intravenous arginine on the healing of human skin graft donor sites: A randomized controlled trial

&lt;p class="Abstract"&gt;We expounded the effect of intravenous arginine on the healing of human skin graft donor sites. This randomized study was double blind and controlled by placebos from October 2012 to May 2015. Nine patients were selected into the arginine group and 10 were selected into the control group. There was no significance in age, weight, BMI, CRP, albumin and total plasma protein in arginine and control groups. Angiogenesis, re-epithelialization and neutrophil influx of wound healing were measured. The concentrations of plasma amino acid were measured to evaluate our intervention. In our study, plasma arginine and ornithine concentrations in arginine group were the highest after arginine-treated at 2 days. Supplementation of intravenous arginine could not affect on healing of human skin graft donor sites, improve angiogenesis, reepithelialization or neutrophil influx in rats.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Oral administration of N-carbamylglutamate might improve growth performance and intestinal function of suckling piglets

The objective of this study was to investigate the effects of oral N-carbamylglutamate (NCG) administration on intestinal digestive enzymes, microbiota population and immunity under physiological condition in newborn piglets. A total of 48 1-d-old piglets (sow reared) were allotted, based on the initial body weights (1.57±0.04kg), into 4 treatments (12 piglets/group): (1) 0.52g/kg body weight (BW) l-Alanine (control), (2) 0.31g/kg BW l-Arginine·HCl (arginine), (3) 0.52g/kg BW l-Alanine plus 50mg/kg BW NCG, and (4) 0.52g/kg BW l-Alanine plus 100mg/kg BW NCG. The supplement were offered twice daily for 14 d. At d 7 and d 14, 6 piglets from each group were killed. Piglets supplemented with 50mg/ kg BW NCG had increased average daily gain during days 1–14 after birth and jejunal mucosal lactase activity on d 7 compared with piglets supplemented with control, arginine and 100mg/kg BW NCG groups. Serum concentrations of arginine, glutamate, citrulline and ornithine in arginine, 50 and 100mg/kg BW NCG groups were markedly increased at d 7 and 14, in comparison with the control group (P<0.05). Moreover, the number of cecal Lactobacillus spp. in both NCG groups was higher than the control and arginine groups at d 14 (P<0.05). Serum IgA (P=0.05) and ileal sIgA (P=0.08) concentrations in the 50mg/kg BW NCG and arginine groups were higher than those in the control and 100mg/kg BW NCG groups at d 14. In conclusion, oral administration of 50mg/kg BW NCG to newborn piglets improved growth performance, increased the endogenous synthesis of arginine and arginine family of amino acids, jejunal lactase activity and cecal Lactobacillus spp. numbers, and stimulated secretion of ileal sIgA.

Nanostructured highly-swollen hydrogels: Complexation with amino acids through copper (II) ions

We report on the complexation of highly swollen poly(methacrylic acid) (PMAA) nanothin hydrogel films with copper (II) ions and the stability of these (PMAA)–Cu2+ complexes in amino acid solutions. These networks are produced by selective cross-linking of PMAA with adipic acid dihydrazide (AAD) and ethylenediamine (EDA) in hydrogen-bonded spin-assisted layer-by-layer films. The swelling of the hydrogels at higher pH values is significantly suppressed after introducing copper (II) ions and can be restored by treatment with amino acid solutions including serine, threonine, arginine, histidine and glutamine. The hydrogel swelling recovery is controlled by Cu2+ removal from the hydrogel which is regulated by the strength of [(PMAA)n–Cu2+] complex bonding and is dependent on the amino acid type, concentration and the hydrogel's cross-linker. The use of AAD as a cross-linker allows for selective binding and recognition of arginine among other amino acids. The special affinity of the [(PMAA)16–AAD–Cu2+] hydrogel complex to arginine is due to the formation of ternary (hydrogel–copper–arginine) complexes stabilized by electrostatic interactions between the carboxylic groups of PMAA and the guanidinium side group of arginine. Our study provides new aspects of competing interactions between polyelectrolyte networks, metal ions, and amino-acids and opens prospects for developing novel analyte-responsive biosensors.

Structural analysis of peptide fragments following the hydrolysis of bovine serum albumin by trypsin and chymotrypsin

Peptide bond hydrolysis of bovine serum albumin (BSA) by chymotrypsin and trypsin was investigated by employing time-resolved fluorescence spectroscopy. As a fluorescent cross-linking reagent, N-(1-pyrenyl) maleimide (PM) was attached to BSA, through all free amine groups of arginine, lysine, and/or single free thiol (Cys34). Time-resolved fluorescence spectroscopy was used to monitor fluorescence decays analyzed by exponential series method to obtain the changes in lifetime distributions. After the exposure of synthesized protein substrate PM-BSA to chymotrypsin and trypsin, it is observed that each protease produced a distinct change in the lifetime distribution profile, which was attributed to distinct chemical environments created by short peptide fragments in each hydrolysate. The persistence of excimer emission at longer lifetime regions for chymotrypsin, as opposed to trypsin, suggested the presence of small-scale hydrophobic clusters that might prevent some excimers from being completely quenched. It is most likely that the formation of these clusters is due to hydrophobic end groups of peptide fragments in chymotrypsin hydrolysate. A similar hydrophobic shield was not suggested for trypsin hydrolysis, as the end groups of peptide fragments would be either arginine or lysine. Overall, in case the target protein’s 3D structure is known, the structural analysis of possible excimer formation presented here can be used as a tool to explain the differences in activity between two proteases, i.e. the peak’s intensity and location in the profile. Furthermore, this structural evaluation might be helpful in obtaining the optimum experimental conditions in order to generate the highest amount of PM-BSA complexes.

Abstract 1348: CD4 T cells targeting citrullinated vimentin reject advanced tumors

Abstract CD4 cells are potent effectors but CD4 responses to tumour associated antigens are attenuated. Cellular stress induces autophagy which leads to modification of proteins recognised by the immune system. In the absence of inflammation, immunity is regulated, whereas in its presence CD4 responses to modified self-antigens are stimulated. T cells commonly target modified self-antigens and have been shown to play a role in the pathophysiology of several autoimmune diseases. In this study the ability of these CD4 cells to target cancer has been explored. One modification is conversion of arginine to citrulline. Peptidylarginine deiminases (PADs), are a family of calcium dependent enzymes found in a variety of tissues, where their role is post translation citrullination of proteins. Citrullination is conversion of the positively charge aldimine group ( = NH) group of arginine to the neutrally charged ketone group ( = O) of citrulline. Immunisation with citrullinated vimentin peptides induced IFNγ and granzyme B secreting CD4 T cells in response to autophagic tumour targets. The induced CD4 responses to citrullinated self-peptide epitopes show minimal reactivity to the unmodified sequence. A single immunization with modified peptide, up to 14 days after tumour implant, resulted in long term survival in 60-90% of animals with no associated toxicity. The anti-tumour responses were dependent upon CD4 but not on CD8 T cells. This study provides the first evidence that tumours can present citrullinated peptides that can be targets for CD4 cells. This presentation is dependent upon autophagy and PAD enzymes. The CD4 T cells release IFNγ and show direct cytotoxicity which results in potent anti-tumour responses in vivo. This approach is being fast tracked into the clinic in patient's whose tumours express vimentin. This could be patients with mesenchymal tumours or in patients whose tumours undergo epithelial to mesenchymal transition as vimentin is one of the first proteins to be expressed in this transition. Citation Format: Lindy G. Durrant, Victoria A. Brentville, Rachael L. Metheringham, Ian Daniels, Peter Symonds, Mohamed Gijon, Wei Xue. CD4 T cells targeting citrullinated vimentin reject advanced tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1348. doi:10.1158/1538-7445.AM2015-1348

Effects of nutritional supplementation with l-arginine on repair of injuries due to muscle strain: experimental study on rats

ObjectiveTo evaluate the influence of oral supplementation with arginine on regeneration of injuries due to straining of the anterior tibial muscle of rats. MethodsTwenty-four Wistar rats of weight 492.5±50.45g were used. Injuries were induced through straining the anterior tibial muscles. The rats were separated into three groups of eight rats each. In the untreated group (UTG), after induction of injuries, the rats were observed for 24h. In the simulation group (SG) and the arginine group (AG) respectively, the rats received isotonic saline solution and arginine solution via direct gavage, over a seven-day period. At the end of the period, blood samples were collected for serum evaluations of creatine kinase (CK), lactic dehydrogenase (LDH), aspartate aminotransferase (AST) and C-reactive protein (CRP). The right and left anterior tibial muscles were resected for histopathological evaluations on the muscle injuries, investigating edema, hemorrhage and disorganization or morphometric alteration of the muscle fibers. The tissue repair was investigated in terms of proliferation of adipose tissue, angiogenesis and collagen fibers. The ANOVA and Student's t methods were used and p≤0.05 was taken to be statistically significant. ResultsIn the serum evaluations, the AG showed lower CK assay values and higher AST values. In the histopathological evaluation, the UTG presented edema and hemorrhage compatible with injuries due to strain; the SG presented edema and hemorrhage with proliferation of adipose tissue and collagen fibers; and the AG presented not only the findings of the SG but also, especially, intense angiogenesis. ConclusionOral supplementation with arginine did not cause any significant metabolic alterations that would contraindicate its use and it induced angiogenesis during the repair of muscles injured due to strain.