Presence Of Histidine Research Articles

Selective fluorescence and naked eye detection of histidine in aqueous medium via hydrogen bonding assisted Schiff base condensation

Visible light excitable rhodamine B derivative (TARDHD) has been developed for fluorescence and naked eye detection of histidine in aqueous medium. TARDHD shows 45 fold fluorescence enhancement in the presence of histidine. It forms Schiff base with histidine and stabilizes via intra-molecular H-bonding. TARDHD can efficiently detect intracellular histidine.

Availability of Zinc and the Ligands Citrate and Histidine to Wheat: Does Uptake of Entire Complexes Play a Role?

Organic ligands in soils affect the availability of trace metals such as Zn to plants. This study investigated the effects of two of these ligands, citrate and histidine, on Zn uptake by wheat under hydroponic conditions. Uptake of (65)Zn in the presence of these ligands was compared to uptake in the presence of EDTA at the same free Zn concentration (Zn(2+) ~ 50 nM). In the presence of citrate Zn root uptake was enhanced ~3.5 times and in the presence of histidine, by a factor of ~9, compared to the EDTA treatments. Citrate uptake was slightly reduced in the treatment containing ligands and Zn compared to the treatment containing the same ligand concentration but no Zn. In addition, a higher uptake of Zn than of citrate was observed. This suggests that the enhanced Zn uptake was primarily due to increased supply of Zn(2+) by diffusion and dissociation of Zn-citrate complexes at the root surface. Histidine uptake was much higher than citrate uptake and not influenced by the presence of Zn. As histidine forms stronger complexes with Zn than citrate, the results suggest that the enhancement of Zn uptake in the presence of histidine was in part due to the uptake of undissociated Zn-histidine complexes.

Comparison of the potential of Ficus sycomorus latex and horseradish peroxidases in the decolorization of synthetic and natural dyes

The aim of this study was to compare the potential of Ficus sycomorus latex peroxidase (POL) and horseradish peroxidase (HRP) in the decolorization of a wide spectrum of eight synthetic dyes and two natural dyes, hibiscus flower color and pomegranate juice. We study for the first time the decolorization of natural dyes enzymatically. The highest decolorization percent was reported at 20 mg/l for all dyes treated with POL and HRP. Both the enzymes had lower decolorization % for azo-carmin (30–33%). During decolorization treatment, both natural dyes and titan yellow formed precipitates which settled down and were removed by centrifugation. The enhancement of the decolorization % of the most tested dyes by treatment with POL and HRP was reported in the presence of some redox mediators. The rate of decolorization was enhanced by increasing the time and the most significant changes were observed during the first 6 h of incubation. One hundred percent enhancement in decolorization was reported for azo-carmine in the presence of histidine and α-naphthol as redox mediators. A few of redox mediators caused no significant effect or decreases the decolorization % for a little number of tested dyes. The decolorization of dyes by POL and HRP in the presence of redox mediators appeared without the formation of precipitate. A similar decolorization % for all the tested dyes by POL and HRP was detected. The data suggested that the peroxidase/mediator system was an effective biocatalyst for the decolorization of synthetic and natural dyes, and POL could be used as a potential option for the application of dye decolorization.

A portable chemical sensor for histidine based on the strategy of click chemistry

A novel portable chemical sensor is developed in combination of the personal glucose meters (PGM) with click chemistry for sensitive and selective determination of histidine. Invertase-labeled alkynyl-DNA can be modified onto the surfaces of Streptavidin Magnespheres Paramagnetic Particles (PMPs) through copper(I) catalyzed azide–alkyne cycloaddition (CuAAC) reaction and formed invertase-functionalized PMPs, which can be separated easily. The presence of invertase can convert sucrose to glucose and can be monitored by the PGM easily. The presence of histidine can inhibit the CuAAC, so the read-out signal of PGM decreased. The difference in signals from the PGM before and after addition of histidine has a good linear correlation with the logarithm of the histidine concentrations in the range of 0.01~100μM with a detection limit of 3.4nM, which is lower than those of many other chemical sensors. Moreover, the assay of histidine in milk samples is demonstrated with satisfactory results.

Incorporation of omega-3 polyunsaturated fatty acids into soybean lecithin: effect of amines and divalent cations on transesterification by lipases

The transesterification of soybean lecithin with methyl esters of EPA and DHA in an organic solvent (hexane) using various commercially available lipases was studied. Lipases produced by Candida antarctica, Pseudomonas fluorescens, Burkholderia cepacia, Mucor miehei, Thermomyces lanuginosus and Rhizomucor miehei were compared, in the absence or presence of histidine, arginine, urea, Ca²⁺, Mg²⁺, or a combination of urea and divalent cations (additives at 5 % of the total lipid mass). Transesterification using the R. miehei enzyme reached 11.32 and 12.30 % in the presence of Ca²⁺ or Mg²⁺ respectively, and 8.58 and 9.31 % when urea was also added. These were the greatest degrees of transesterification obtained. The results suggest the potential use of this immobilized lipase as a catalyst for interesterification reactions in organic solvent systems with low water content.

Electrochemical reduction and oxidation signals of angiotensin peptides. Role of individual amino acid residues

Chronopotentiometric stripping (CPS) peak H in proteins is due to the catalytic hydrogen evolution reaction (CHER) involving amino acid residues. This peak is sensitive to changes in protein structures, representing a new tool in protein research. Here we show on the ground of studies of CPS behavior of four angiotensin peptides that at neutral pH arginine plays a critical role in CHER at Hg electrode, while participation of histidine residues in this reaction is very weak. At carbon electrode tyrosine residues produce an oxidation peak close to 0.7V but the presence of histidine in angiotensins is not manifested by any oxidation peak.

Stability of core/shell quantum dots—role of pH and small organic ligands

The improvement of knowledge about the toxicity and even processability, and stability of quantum dots (QD) requires the understanding of the relationship between the QD binding head group, surface structure, and interligand interaction. The scanned stripping chronopotentiometry and absence of gradients and Nernstian equilibrium stripping techniques were used to determine the concentration of Cd dissolved from a polyacrylate-stabilized CdTe/CdS QD. The effects of various concentrations of small organic ligands such as citric acid, glycine, and histidine and the roles of pH (4.5-8.5) and exposure time (0-48 h) were evaluated. The highest QD dissolution was obtained at the more acidic pH in absence of the ligands (52%) a result of the CdS shell solubility. At pH 8.5 the largest PAA ability to complex the dissolved Cd leads to a further QD solubility until the equilibrium is reached (24% of dissolved Cd vs. 4% at pH 6.0). The citric acid presence resulted in greater QD dissolution, whereas glycine, an amino acid, acts against QD dissolution. Surprisingly, the presence of histidine, an amino acid with an imidazole functional group, leads to the formation of much strong Cd complexes over time, which may be non-labile, inducing variations in the local environment of the QD surface.

Highly selective fluorescent recognition of histidine by a crown ether–terpyridine–Zn(ii) sensor

A Zn(II) complex was found to exhibit greatly enhanced fluorescence in the presence of histidine but not in the presence of any other amino acids including cysteine. This sensor could also distinguish histidine from other imidazole derivatives.

Selective Isolation of Multiply Charged Peptides: A Confident Strategy for Protein Identification Using a Linear Trap Quadrupole Mass Spectrometer

In this work, a method devised for the selective isolation of multiply-charged peptide applied to a complex protein mixture was evaluated for the first time using a mass spectrometer with low resolution (LTQ). In this procedure, all primary amino groups of tryptic peptides derived from human Liver tissue interstitial fluid (TIF) are blocked, restricting their positive charge, at acidic pH, to the presence of histidine and arginine residues. After strong cation exchange chromatography, multiply-charged peptides (#R+#H > 1) are retained in the column and separated with high selectivity from singly (#R+#H = 1) and neutral peptides (#R +#H = 0) which are collected together in the flow-through. Using Liquid chromatography electrospray ionization tandem mass spectrometry analysis the retained fraction displayed a 95% enrichment of multiply charged peptides while in the flow-through; only 4% of multiply-charged peptides were identified.

Mutational analysis in the glycone binding pocket of Dalbergia cochinchinensis β-glucosidase to increase catalytic efficiency toward mannosides

Dalcochinase and Abg are glycoside hydrolase family 1 β-glucosidases from Dalbergia cochinchinensis Pierre and Agrobacterium sp., respectively, with 35% sequence identity. However, Abg shows much higher catalytic efficiencies toward a broad range of glycone substrates than dalcochinase does, possibly due to the difference in amino acid residues around their glycone binding pockets. Site-directed mutagenesis was used to replace the amino acid residues of dalcochinase with the corresponding residues of Abg, generating three single mutants, F196H, S251V, and M369E, as well as the corresponding three double mutants and one triple mutant. Among these, the F196H mutant showed increases in catalytic efficiency toward almost all glycoside substrates tested, with the most improved catalytic efficiency being a 3-fold increase for hydrolysis of p-nitrophenyl β-d-mannoside, suggesting a preferred polar residue at this position and consistent with the presence of histidine at this position in two other GH1 glycosidases from barley and rice that prefer β-mannosides. In addition, the M369E mutation resulted in a small increase in catalytic efficiency for cleavage of p-nitrophenyl β-d-galactoside. By contrast, the multiple mutants were up to 8-fold less efficient than the recombinant wild-type dalcochinase, and displayed primarily antagonistic interactions between these residues. Thus, differences in catalytic efficiency between dalcochinase and Abg are therefore not primarily due to differences in the residues that directly contact the substrate, but derive largely from contributions from more remote residues and the overall architecture of the active site.

MALDI mass sequencing and biochemical characterization of Setaria cervi protein tyrosine phosphatase

A 30-kDa acid phosphatase with protein tyrosine phosphatase activity was identified in Setaria cervi (ScPTP). The enzyme was purified to homogeneity using three-step column chromatography. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis of purified ScPTP yielded a total of eight peptides matching most closely to phosphoprotein phosphatase of Ricinus communis (RcPP). A hydrophilicity plot of RcPP revealed the presence of these peptides in the hydrophilic region, suggesting their antigenic nature. The substrate specificity of ScPTP with ortho-phospho-L-tyrosine and inhibition with sodium orthovanadate and ammonium molybdate affirmed it as a protein tyrosine phosphatase. ScPTP was also found to be tartrate resistant. The Km and Vmax were 6.60mM and 83.3μM/ml/min, respectively, with pNPP and 8.0mM and 111μM/ml/min, respectively, with ortho-phospho-L-tyrosine as the substrate. The Ki value with sodium orthovanadate was calculated to be 16.10mM. Active site modification with DEPC, EDAC and pHMB suggested the presence of histidine, cysteine and aspartate at its active site. Thus, on the basis of MALDI-TOF and biochemical studies, it was confirmed that purified acid phosphatase is a PTP.

G-quadruplex-based ultrasensitive and selective detection of histidine and cysteine

Histidine and cysteine detection is critically important since an abnormal level of histidine or cysteine is an indicator for many diseases. In this paper, we demonstrated a novel label-free, G-quadruplex-based approach for simultaneous detection of histidine and cysteine. The present assay is based on the highly specific interaction among amino acids (histidine or cysteine), Cu2+ and NMM/G-4 (NMM: N-methylmesoporphyrin IX; G-4: G-quadruplex). The fluorescence intensity of NMM was dramatically enhanced in the presence of G-quadruplex formed from 24GT, which can be effectively quenched by cupric ion (Cu2+) due to the chelation of Cu2+ by NMM as well as the unfolding of G-quadruplex by Cu2+. The presence of histidine or cysteine will disturb the interaction between Cu2+ and NMM/G-4 because of the strong binding affinity of Cu2+ to the imidazole group of histidine or the interaction of Cu2+ with thiol group in cysteine, leading to distinct fluorescence emission intensity. High selectivity is conferred by the use of cysteine-masking agent N-ethylmaleimide (NEM), which helps to discriminate histidine from cysteine. At last, a novel and simple approach was developed to determine each precise concentration of histidine and cysteine according to the different response of the system with and without NEM. Importantly, histidine can be also detected even in the presence of a large amount of other amino acids. A detection limit as low as 3nM for histidine and 5nM for cysteine was obtained by practical measurement rather than conventional calculation (S/N=3), confirming the high sensitivity of the present approach. Meanwhile, this sensing protocol can determine histidine and cysteine in diluted biological samples such as urine, exhibiting great potential to meet the need of practical application.

Improved Acid Stress Survival of Lactococcus lactis Expressing the Histidine Decarboxylation Pathway of Streptococcus thermophilus CHCC1524

Degradative amino acid decarboxylation pathways in bacteria generate secondary metabolic energy and provide resistance against acid stress. The histidine decarboxylation pathway of Streptococcus thermophilus CHCC1524 was functionally expressed in the heterologous host Lactococcus lactis NZ9000, and the benefits of the newly acquired pathway for the host were analyzed. During growth in M17 medium in the pH range of 5-6.5, a small positive effect was observed on the biomass yield in batch culture, whereas no growth rate enhancement was evident. In contrast, a strong benefit for the engineered L. lactis strain was observed in acid stress survival. In the presence of histidine, the pathway enabled cells to survive at pH values as low as 3 for at least 2 h, conditions under which the host cells were rapidly dying. The flux through the histidine decarboxylation pathway in cells grown at physiological pH was under strict control of the electrochemical proton gradient (pmf) across the membrane. Ionophores that dissipated the membrane potential (ΔΨ) and/or the pH gradient (ΔpH) strongly increased the flux, whereas the presence of glucose almost completely inhibited the flux. Control of the pmf over the flux was exerted by both ΔΨ and ΔpH and was distributed over the transporter HdcP and the decarboxylase HdcA. The control allowed for a synergistic effect between the histidine decarboxylation and glycolytic pathways in acid stress survival. In a narrow pH range around 2.5 the synergism resulted in a 10-fold higher survival rate.

Structural rearrangements and chemical modifications in known cell penetrating peptide strongly enhance DNA delivery efficiency

Amphipathic peptides with unusual cellular translocation properties have been used as carriers of different biomolecules. However, the parameters which control the delivery efficiency of a particular cargo by a peptide and the selectivity of cargo delivery are not very well understood. In this work, we have used the known cell penetrating peptide pVEC (derived from VE-cadherin) and systematically changed its amphipathicity (from primary to secondary) as well as the total charge and studied whether these changes influence the plasmid DNA condensation ability, cellular uptake of the peptide–DNA complexes and in turn the efficiency of DNA delivery of the peptide. Our results show that although the efficiency of DNA delivery of pVEC is poor, modification of the same peptide to create a combination of nine arginines along with secondary amphipathicity improves its plasmid DNA delivery efficiency, particularly in presence of an endosomotropic agent like chloroquine. In addition, presence of histidines along with 9 arginines and secondary amphipathicity shows efficient DNA delivery with low toxicity even in absence of chloroquine in multiple cell lines. We attribute these enhancements in transfection efficiency to the differences in the mechanism of complex formation by the different variants of the parent peptide which in turn are related to the chemical nature of the peptide itself. These results exhibit the importance of understanding the physicochemical parameters of the carrier and complex in modulating gene delivery efficiency. Such studies can be helpful in improving peptide design for delivery of different cargo molecules.

Adaptation by stochastic switching of a monostable genetic circuit in Escherichia coli

Stochastic switching is considered as a cost-saving strategy for adaptation to environmental challenges. We show here that stochastic switching of a monostable circuit can mediate the adaptation of the engineered OSU12-hisC Escherichia coli strain to histidine starvation. In this strain, the hisC gene was deleted from the His operon and placed under the control of a monostable foreign promoter. In response to histidine depletion, the OSU12-hisC population shifted to a higher HisC expression level, which is beneficial under starving conditions but is not favoured by the monostable circuit. The population shift was accompanied by growth recovery and was reversible upon histidine addition. A weak directionality in stochastic switching of hisC was observed in growing microcolonies under histidine-free conditions. Directionality and fate decision were in part dependent on the initial cellular status. Finally, microarray analysis indicated that OSU12-hisC reorganized its transcriptome to reach the appropriate physiological state upon starvation. These findings suggest that bacteria do not necessarily need to evolve signalling mechanisms to control gene expression appropriately, even for essential genes.

FCgammaRIIa Polymorphism Is Not Associated with Overall Response, Progression Free Survival and Overall Survival In Diffuse Large B-Cell Lymphoma Treated with Rituximab

AbstractAbstract 5078 Background:Low-affinity receptor for the Fcγ region of immunoglobulin G (IgG) (FcγR) is constitutively expressed on resting human neutrophils. These receptor, termed FcγRIIa display biallelic polymorphism which have functional consequences with respect to binding and/or ingestion of targets opsonized by human IgG subclass antibodies. Rituximab is a chimeric monoclonal antibody directed against CD20, an antigen found in most B-cell malignancies. Multiple mechanisms have been proposed for the activity of Rituximab, including antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and a direct proapoptotic effect. F(ab′)2 Rituximab homodimers were shown to be effective in inducing apoptosis of B-cell lymphoma cell lines in vitro. Recently, it have been established that ADCC is important as predominant mechanism of lymphoma cell clearance and that Fcγ receptors (FcγRs) are critical for the in vivo actions of Rituximab in non-Hodgkin lymphoma (NHL). A genomic polymorphism at amino acid 131 of FcγRIIA has been described whereby the presence of Histidine (H) rather than Arginine is associated with responses to the CD20-directed immunoglobulin G1 (IgG1) Rituximab among patients with indolent lymphoma. FcγRIIA genotype have been associated with a better clinical and molecular response in follicular lymphoma patients treated as first line therapy with Rituximab alone and in patients with diffuse large B-cell lymphoma (DLBCL) treated with the concomitant administration of Rituximab and CHOP (R-CHOP). Methods:Here we analyzed the role of specific polymorphism of activating FcγRIIA in 64 patients with DLBCL treated with R-CHOP concerning prediction complete response (CR), Progression Free Survival (PFS) and Overall Survival (OS) using a polymerase chain reaction-restriction fragment length polymorphism method. Results:The median age of the patients was 48.6 years. Out of the 64 patients (32%), were stage III-IV and 27 (42.5%) had more than 2 factors of the International Prognostic Index. Fity-six (89%) had CR and 7 (9.5%) had refractory disease (RD). Seven (11%) of the patients presented relapses. Deaths occurred in 6 (9.3%) patients with follow up of 19,5 months (range 21,3-50,1). The distribution of FcγRIIA polymorphism genotypes was: 15 (23,4%) HH, 30(46,9%) HR and 19(29,7%) RR, while considering only two groups (HH and R allele (HR and RR) was 15 (23,4%) and 49 (76,6%). There were no statistically significant differences in the genotypes groups according prognostic factors. In addition, there were not differences between response rate and FcγRIIA genotypes polymorphism: the CR in HH and HR/ RR were respectively 80% and 89%, p=0,377. It was not found differences regarding FcγRIIa. HH genotype presented a median PFS and OS. Thus, PFS HH genotype presented a median PFS 20,96 ± 10,49 months versus HR/RR median PFS 12,03 ± 7,71 months, p = 0,765, and OS 23,26 ± 10,42 months versus HR/ RR median OS 12,7 ± 7,42 months, p =0,98. Conclusions:Contrary to recent report we showed that FcγRIIA polymorphism is not associated to overall response, PFS and OS in patients with DLBCL treated with R-CHOP. Disclosures:No relevant conflicts of interest to declare.

Impact of heme reconstitution on the spectroscopic properties and DNA binding activity of the H82A variant of the carbon monoxide‐sensing heme transcription factor, CooA

CooA is a gas‐sensing heme protein that regulates the expression of genes responsible for growth by carbon monoxide (CO) in several bacteria. CO binding to the CooA heme groups results in an allosteric conformation change that initiates the protein's DNA binding function. All known CooA homologs have a conserved histidine residue that i) acts as the proximal heme ligand and ii) is trans to CO. Together with the results from mutagenesis studies, this observation suggests the presence of a proximal histidine ligand is required for CooA's DNA‐binding activity. However, since mutants lacking this His have been observed to lose heme upon purification, an alternative hypothesis is that the absence of heme, and not the presence of histidine per se, accounts for this loss of function. To test this hypothesis, we measured the spectroscopic properties and DNA‐binding activity of heme‐reconstituted H82A. Results obtained using electronic absorbance spectroscopy suggest heme‐reconstituted Fe(II)‐CO H82A has an iron environment similar to that of wild‐type CooA. Preliminary results from a fluorescence anisotropy assay also reveal that reconstituted H82A possesses modest DNA binding activity, which suggests the presence of His‐82 is not essential for this activity. The authors wish to thank the Valparaiso University College of Arts and Sciences for financial support.

Tuning the band gap of ZnO nanoparticles by ultrasonic irradiation

In this present paper, we report the tunability of ZnO nanoparticles by ultrasonic irradiation. Different sized ZnO nanoparticles viz. 2.58–2.97 nm have been synthesized with variation of ultrasonic irradiation time 75–270 min in presence of Histidine as capping agent. UV and visible spectroscopy study revealed that as ultrasonic irradiation time increases, there is increase in amount of formed ZnO nanoparticles and also there is red shift in absorption edge. This confirms the tunability of bandgap of histidine capped ZnO nanoparticles with ultrasonic irradiation. Growth mechanism for controlling the size of ZnO nanoparticles are also discussed.

Selective Isolation—Detection of Two Different Positively Charged Peptides Groups by Strong Cation Exchange Chromatography and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry: Application to Proteomics Studies

We report here a procedure for the independent analysis of two groups of peptides by liquid chromatography-matrix-assisted laser desorption/ionization mass spectrometry (LC-MALDI MS/MS), using a selective isolation-detection procedure. In this procedure all primary amino groups of tryptic peptides derived from mouse liver proteins are blocked, restricting their positive charge, at acidic pH, to the presence of histidine and arginine residues. After strong cation exchange chromatography, multiply charged peptides (R + H > 1) are retained on the column and separated with high selectivity from singly (R + H = 1) and neutral peptides (R + H = 0) which are together collected in the flow-through. Using LC-MALDI-MS/MS analysis, the retained fraction displayed a 94% of enrichment of multiply charged peptides while in the flow-through; peptides with at least one arginine or histidine residue were exclusively identified, which suggests that MS detection in this fraction is restricted only to those peptides with ionizable side chains, arginine and histidine amino acids.

Arginine in the salt-induced peptide formation reaction: enantioselectivity facilitated by glycine, l- and d-histidine

The salt-induced peptide formation reaction has been proposed as a conceivable preliminary to the prebiotic evolution of peptides. In the present paper, the behaviour of arginine is reported for this reaction together with a discussion of the catalytic effects of glycine, and L- and D-histidine. Importantly, the behaviour of the two histidine enantiomers is different. Both histidine enantiomers perform better than glycine in enhancing the yields of arginine dipeptide with L-histidine being more effective than D-histidine. Yields in the presence of histidine are up to 70 times greater than for arginine solutions alone. This compares with 4.2 times higher in the presence of glycine. This difference is most pronounced in the most concentrated (containing 80 mM arginine) reaction solution where arginine has the lowest reactivity. A distinct preference for dimerisation of L-arginine also appears in the 80 mM cases for catalyses of other amino acids. This phenomenon is different from the behaviour of aliphatic amino acids, which display obvious inherent enantioselectivity for the L-stereomers in the SIPF reaction on their own rather than when catalysed by glycine or histidine.