Concentrations Of L-lysine Research Articles

Comparison of the physical stability, microstructure and protein-lipid co-oxidation of O/W emulsions stabilized by l-arginine/l-lysine-modified soy protein hydrolysate

This work investigated the physical stability, microstructure, and oxidative stability of the emulsions prepared by soy protein hydrolysate (SPH) after modification with different concentrations of l-arginine and l-lysine. l-Arginine and l-lysine significantly increased the absolute zeta potential values, and decreased droplet sizes of the emulsions, thereby improving the physical stability of the emulsions. Meanwhile, l-arginine and l-lysine markedly decreased the apparent viscosity of the emulsions. The measurement of interfacial protein adsorption percentage showed that l-arginine (≤0.5 %) promoted the adsorption of SPH at the oil–water interface, whereas l-lysine (≤1%) reduced the adsorption of SPH at the oil–water interface. In addition, l-arginine and l-lysine (≤0.5 %) could retard lipid and protein oxidation. Correlation analysis indicated that the improvement in the physical stability of the emulsions by l-arginine and l-lysine also enhanced the oxidative stability of the emulsions. In summary, l-arginine and l-lysine could be effective modifiers for the protein-based emulsion systems.

The recipient metabolome explains the asymmetric ovarian impact on fetal sex development after embryo transfer in cattle.

In cattle, lateral asymmetry affects ovarian function and embryonic sex, but the underlying molecular mechanisms remain unknown. The plasma metabolome of recipients serves to predict pregnancy after embryo transfer (ET). Thus, the aim of this study was to investigate whether the plasma metabolome exhibits distinct lateral patterns according to the sex of the fetus carried by the recipient and the active ovary side (AOS), i.e., the right ovary (RO) or the left ovary (LO). We analyzed the plasma of synchronized recipients by 1H+NMR on day 0 (estrus, n = 366) and day 7 (hours prior to ET; n = 367). Thereafter, a subset of samples from recipients that calved female (n = 50) or male (n = 69) was used to test the effects of embryonic sex and laterality on pregnancy establishment. Within the RO, the sex ratio of pregnancies carried was biased toward males. Significant differences (P < 0.05) in metabolite levels were evaluated based on the day of blood sample collection (days 0, 7 and day 7/day 0 ratio) using mixed generalized models for metabolite concentration. The most striking differences in metabolite concentrations were associated with the RO, both obtained by multivariate (OPLS-DA) and univariate (mixed generalized) analyses, mainly with metabolites measured on day 0. The metabolites consistently identified through the OPLS-DA with a higher variable importance in projection score, which allowed for discrimination between male fetus- and female fetus-carrying recipients, were hippuric acid, l-phenylalanine, and propionic acid. The concentrations of hydroxyisobutyric acid, propionic acid, l-lysine, methylhistidine, and hippuric acid were lowest when male fetuses were carried, in particular when the RO acted as AOS. No pathways were significantly regulated according to the AOS. In contrast, six pathways were found enriched for calf sex in the day 0 dataset, three for day 7, and nine for day 7/day 0 ratio. However, when the AOS was the right, 20 pathways were regulated on day 0, 8 on day 7, and 13 within the day 7/day 0 ratio, most of which were related to amino acid metabolism, with phenylalanine, tyrosine, and tryptophan biosynthesis and phenylalanine metabolism pathways being identified throughout. Our study shows that certain metabolites in the recipient plasma are influenced by the AOS and can predict the likelihood of carrying male or female embryos to term, suggesting that maternal metabolism prior to or at the time of ET could favor the implantation and/or development of either male or female embryos.

Structural basis of enzyme activity regulation by the propeptide of l-lysine α-oxidase precursor from Trichoderma viride

Harmuful proteins are usually synthesized as inactive precursors and are activated by proteolytic processing. l-Amino acid oxidase (LAAO) is a flavoenzyme that catalyzes the oxidative deamination of l-amino acid to produce a 2-oxo acid with ammonia and highly toxic hydrogen peroxide and, therefore, is expressed as a precursor. The LAAO precursor shows significant variation in size and the cleavage pattern for activation. However, the molecular mechanism of how the propeptide suppresses the enzyme activity remains unclear except for deaminating/decarboxylating Pseudomonasl-phenylalanine oxidase (PAO), which has a short N-terminal propeptide composed of 14 residues. Here we show the inactivation mechanism of the l-lysine oxidase (LysOX) precursor (prLysOX), which has a long N-terminal propeptide composed of 77 residues, based on the crystal structure at 1.97 Å resolution. The propeptide of prLysOX indirectly changes the active site structure to inhibit the enzyme activity. prLysOX retains weak enzymatic activity with strict specificity for l-lysine and shows raised activity in acidic conditions. The structures of prLysOX crystals that soaked in a solution with various concentrations of l-lysine have revealed that prLysOX can adopt two conformations; one is the inhibitory form, and the other is very similar to mature LysOX. The propeptide region of the latter form is disordered, and l-lysine is bound to the latter form. These results indicate that prLysOX uses a different strategy from PAO to suppress the enzyme activity and suggest that prLysOX can be activated quickly in response to the environmental change without proteolytic processing.

Peptidoglycan Sensing Prevents Quiescence and Promotes Quorum-Independent Colony Growth of Uropathogenic Escherichia coli.

Uropathogenic Escherichia coli (UPEC) is the leading cause of human urinary tract infections (UTIs), and many patients experience recurrent infection after successful antibiotic treatment. The source of recurrent infections may be persistent bacterial reservoirs in vivo that are in a quiescent state and thus are not susceptible to antibiotics. Here, we show that multiple UPEC strains require a quorum to proliferate in vitro with glucose as the carbon source. At low cell density, the bacteria remain viable but enter a quiescent, nonproliferative state. Of the clinical UPEC isolates tested to date, 35% (51/145) enter this quiescent state, including isolates from the recently emerged, multidrug-resistant pandemic lineage ST131 (i.e., strain JJ1886) and isolates from the classic endemic lineage ST73 (i.e., strain CFT073). Moreover, quorum-dependent UPEC quiescence is prevented and reversed by small-molecule proliferants that stimulate colony formation. These proliferation cues include d-amino acid-containing peptidoglycan (PG) tetra- and pentapeptides, as well as high local concentrations of l-lysine and l-methionine. Peptidoglycan fragments originate from the peptidoglycan layer that supports the bacterial cell wall but are released as bacteria grow. These fragments are detected by a variety of organisms, including human cells, other diverse bacteria, and, as we show here for the first time, UPEC. Together, these results show that for UPEC, (i) sensing of PG stem peptide and uptake of l-lysine modulate the quorum-regulated decision to proliferate and (ii) quiescence can be prevented by both intra- and interspecies PG peptide signaling.IMPORTANCE Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections (UTIs). During pathogenesis, UPEC cells adhere to and infiltrate bladder epithelial cells, where they may form intracellular bacterial communities (IBCs) or enter a nongrowing or slowly growing quiescent state. Here, we show in vitro that UPEC strains at low population density enter a reversible, quiescent state by halting division. Quiescent cells resume proliferation in response to sensing a quorum and detecting external signals, or cues, including peptidoglycan tetra- and pentapeptides.

Evaluation of the effect of berry extracts on carboxymethyllysine and lysine in ultra-high temperature treated milk.

Both the Maillard reaction (MR) and thermal treatment influence the nutritional value of milk. In this paper, the capability of polyphenolic berry extract (PBE) to inhibit MR in an ultra-high temperature (UHT) treated milk was investigated. Total polyphenol content and antioxidant capacity of blueberry (BE) and raspberry extracts (RE) were also tested. A gas chromatography-mass spectrometry (GC-MS) method was developed to monitor the MR product N ε-(carboxymethyl)-L-lysine (CML) and L-lysine (LYS). PBE was added to milk at 0.05 and 0.1% w/v prior to UHT processing. Data revealed that formation of CML was significantly reduced (23.4±5.1%) by addition of 0.1% w/v BE. The final concentrations of LYS measured following the addition of PBE prior to thermal treatment were statistically similar to the control milk which was not subjected to thermal processing. Additionally, the metabolic profile of milk samples was investigated by GC-MS and visualised using 'FancyTiles'.

L-Arginine metabolism alteration by L-Lysine intervention increased cell death in triple negative breast cancer cell

Abstract Background L-Arginine effectiveness cancer therapy is a matter of controversy. L-Arginine is a substrate for different metabolites influencing cancer cells. Arginase and nitric oxide synthase (NOS) are two important enzymes in the L-Arginine metabolic pathway. Nitric oxide (NO) is produced by NOS and the main products of arginase activity are polyamines. NO can decrease cancer cells viability dependent on its concentration but, polyamines shown to promote cancer cell growth/metastasis. Due to Arginase and NOS competition over L-Arginine binding, inhibition of arginase activity seems to increase NOS activity as well as NO production. Thus, the aim of the present study is to affect L-Arginine metabolic pathway through L-Lysine induced arginase inhibition in MDA-MB-231 and MDA-MB-468 Methods MDA-MB-231 and MDA-MB-468 were used as triple negative breast cancer cells with different arginase activity. Both cell lines were treated with different concentrations of L-Arginine and L-Lysine. Cell viability was assessed by MTT assay 24 and 48h after treatment. Arginase activity, ROS level and NO concentration was examined. Cell cycle was assessed using flowcytometry. Real-time PCR was performed to assess apoptotic and metabolic genes expression Results Our results indicated that cell viability and arginase activity were decreased in MDA-MB-468 with high arginase level more than MDA-MB-231 and studying the cell cycle also showed G2/M arrest in both cell lines following combination treatment with L-Lysine with L-Arginine. L-Lysine treatment resulted in increased apoptotic genes and decreased metabolic related genes expression in both cell lines Conclusion Altogether, our findings indicated that alternation in L-Arginine metabolic pathway using L-Lysine causes higher NO concentration which consequently increases cell death in triple negative breast cancer cells with different arginase level, which in turn can increase L-Arginine effect on cell lines with higher arginase activity

L-Lysine increased the cytotoxicity effect of doxorubicin in MDA-MB-231 and MDA-MB-468 breast cancer cell lines

Abstract Background Breast cancer is the first cause of death among Women. Chemoresistance is believed to be responsible for most of the mortalities, thus using new therapeutic strategies are needed. Autophagy has been shown as a critical player in cancer cells response to chemotherapeutic drugs such as doxorubicin. However, autophagy effect on cancer cell can be viewed as a pro-death or a pro-survival role. Thus, increase or decrease of this process in cells relative to its baseline can induce cancer cell death. Thus, we investigated if L-Lysine can increase doxorubicin effectiveness in combination therapy through autophagy modulation. Methods MDA-MB-231 and MDA-MB-468 were used as two breast cancer cell lines. Cells were treated with various concentrations of doxorubicin and L-Lysine. Cell viability was assessed using MTT assay 24 and 48h after treatment. ROS and NO level was examined and the expression of various autophagy and apoptosis related proteins/genes were evaluated with western blotting and real-time PCR respectively. Results L-Lysine increased cytotoxicity effect of doxorubicin in both MDA-MB-231 and MDA-MB-468 by autophagy enhancement. L-Lysine reduced cell viability and increased apoptosis in combination with doxorubicin. Real-time PCR analysis indicated that the combination of these two drugs resulted in increased autophagy as well as apoptosis-related genes. Moreover, reactive oxygen species (ROS) and nitric oxide (NO) production increased 30min after treatment with both drugs. However, the amount of these molecules decreased after 24h which can be results of autophagy induction. These results were further confirmed at protein levels of LC-3 and mTOR by western blotting. Conclusion Our findings indicated that L-Lysine can reduce the resistance to doxorubicin in triple negative breast cancer cells, MDA-MB-231 and MDA-MB-468. Therefore combination therapy with L-Lysine and doxorubicin could be consider an effective strategy in breast cancer therapy.

Enhanced production of cadaverine by the addition of hexadecyltrimethylammonium bromide to whole cell system with regeneration of pyridoxal-5′-phosphate and ATP

Cadaverine, also known as 1,5-pentanediamine, is an important platform chemical with a wide range of applications and can be produced either by fermentation or bioconversion. Bioconversion of cadaverine from l-lysine is the preferred method because of its many benefits, including rapid reaction time and an easy downstream process. In our previous study, we replaced pyridoxal-5-phosphate (PLP) with pyridoxal kinase (PdxY) along with pyridoxal (PL) because it could achieve 80% conversion with 0.4 M of l-lysine in 6 h. However, conversion was sharply decreased in the presence of high concentrations of l-lysine (i.e., 1 M), resulting in less than 40% conversion after several hours. In this study, we introduced an ATP regeneration system using polyphosphate kinase (ppk) into systems containing cadaverine decarboxylase (CadA) and PdxY for a sufficient supply of PLP, which resulted in enhanced cadaverine production. In addition, to improve transport efficiency, the use of surfactants was tested. We found that membrane permeabilization via hexadecyltrimethylammonium bromide (CTAB) increased the yield of cadaverine in the presence of high concentrations of l-lysine. By combining these two strategies, the ppk system and addition of CTAB, we enhanced cadaverine production up to 100% with 1 M of l-lysine over the course of 6 h.

Improved growth performance, food efficiency, and lysine availability in growing rats fed with lysine-biofortified rice

Rice is an excellent source of protein, and has an adequate balance of amino acids with the exception of the essential amino acid lysine. By using a combined enhancement of lysine synthesis and suppression of its catabolism, we had produced two transgenic rice lines HFL1 and HFL2 (High Free Lysine) containing high concentration of free lysine. In this study, a 70-day rat feeding study was conducted to assess the nutritional value of two transgenic lines as compared with either their wild type (WT) or the WT rice supplemented with different concentrations of L-lysine. The results revealed that animal performance, including body weight, food intake, and food efficiency, was greater in the HFL groups than in the WT group. Moreover, the HFL diets had increased protein apparent digestibility, protein efficiency ratio, and lysine availability than the WT diet. Based on the linear relationship between dietary L-lysine concentrations and animal performance, it indicated that the biological indexes of the HFL groups were similar or better than that of the WT20 group, which was supplemented with L-lysine concentrations similar to those present in the HFL diets. Therefore, lysine-biofortified rice contributed to improved growth performance, food efficiency, and lysine availability in growing rats.

New enzymatic methods for selective assay of l-lysine using an l-lysine specific decarboxylase/oxidase from Burkholderia sp. AIU 395

We developed new enzymatic methods for the selective assay of L-lysine by utilizing an oxidase reaction and a decarboxylation reaction by the L-lysine-specific decarboxylase/oxidase (L-Lys-DC/OD) from Burkholderia sp. AIU 395. The method utilizing the oxidase reaction of this enzyme was useful for determination of high concentrations of L-lysine. The method utilizing the decarboxylase reaction, which proceeded via the combination of the L-Lys-DC/OD and putrescine oxidase (PUO) from Micrococcus rubens, was effective for determination of low concentrations of L-lysine. Both methods showed good linearity, and neither was affected by other amino acids or amines. In addition, the within-assay and between-assay precisions of both methods were within the allowable range. The coupling of L-Lys-DC/OD with PUO was also useful for the differential assay of L-lysine and cadaverine. These newly developed methods were applied to the assay of L-lysine in biological samples and found to be effective.

Gastrointestinal tract response and growth performance of growing turkeys as influenced by the whole wheat content of diets in two feeding programmes

The objective of this study was to determine the physiological re- sponses and growth performance of turkeys fed 20% whole wheat (WW) in two feeding programmes, diets A and B, consistent with the NRC (1994) and B.U.T. (2012) recommendations, respectively. In diet B, in successive feeding periods (weeks 5-18), the soyabean meal content was increased by 2.89% to 5.13%, the wheat content was decreased by 5.29% to 8.18%, and the concentrations of L-lysine, DL-methionine and L-threonine were considerably increased. A total of 896 four-week-old Big-6 male turkeys with similar initial body weights were randomly assigned to four equal dietary treatment groups, with seven replicate pens per treatment. The birds had free access to water and pelleted diets that contained no WW or 20% WW. After 14 weeks of feeding, the body weight gains (BWG) of turkeys were similar in all dietary treatments. From week 13 to 18, WW contributed to a significant ( P = 0.040) increase in the feed conversion ratio (FCR), whereas the increase in FCR noted over the entire experiment was nearly significant ( P = 0.065). Dietary inclusion of WW had no effect on the weights of the gizzard, small intestine, or caecum, and it enhanced fermentation in the caecum, including increasing α-glucosidase activity and the concentra- tions of total short-chain fatty acids, and decreasing the pH of caecal digesta (all P = 0.001). No significant differences were noted in the parameters of gastroin - testinal function and BWG between turkeys fed diets A and B. Diet B did, how- ever, significantly (P = 0.045) improve FCR over the entire experiment.

Effects of physiologic concentrations of l-lysine on in vitro replication of feline herpesvirus 1.

To evaluate the effects of various concentrations of l-lysine on in vitro replication of feline herpesvirus 1 (FHV-1). Cultures of Crandell-Rees feline kidney (CRFK) cells. CRFK cells were inoculated with FHV-1 and maintained in media with 20 combinations of l-arginine and l-lysine concentrations. Changes in cell viability were monitored by continuous measurement of electrical impedance of cultured cells and by observation of viral cytopathic effects. Viral load was determined by use of quantitative PCR assay in supernatants obtained from infected cultures at specified time points. Increases in l-lysine concentration had no effect on the kinetics of cell death in FHV-1-infected cultures. There was also no significant effect (r(2) < 0.1) on viral DNA load for l-arginine concentrations ≥ 12 μg/mL There was a significant effect of increases in l-lysine concentration on viral DNA load in media supplemented with 6 μg of l-arginine/mL (mean ± SD slope, -4,641 ± 1,626 units; adjusted r(2) = 0.45). However, the difference between the lowest (1 × 10(6.28) copies/μL) and highest (1 × 10(6.86) copies/μL) FHV-1 DNA load in these media was < 1 logarithm. The difference in FHV-1 DNA load was unlikely to be biologically important. Various l-lysine concentrations did not inhibit in vitro replication of FHV-1 at l-arginine concentrations sufficient to maintain cell growth. This conclusion was consistent with results of other studies in which investigators have not detected a consistently beneficial effect when l-lysine is administered to FHV-1-infected cats.

Enhancing l-Isoleucine Production by thrABC Overexpression Combined with alaT Deletion in Corynebacterium glutamicum

L-isoleucine is synthesized from 2-ketobutyrate and pyruvate in Corynebacterium glutamicum, and the supplies of these two precursors are important for L-isoleucine synthesis. C. glutamicum YILWΔalaT with alaT gene deletion (encoding alanine aminotransferase, a principal enzyme for L-alanine synthesis) was constructed to increase intracellular pyruvate availability, and the thrABC genes from Escherichia coli (encoding bifunctional aspartate kinase I-homoserine dehydrogenase I, homoserine kinase, and threonine synthetase) were overexpressed in C. glutamicum YILW and YILWΔalaT to increase the supply of intracellular 2-ketobutyrate. In the fed-batch fermentation, YILWpXMJ19thrABC, YILWΔalaT, and YILWΔalaTpXMJ19thrABC exhibited 5.3, 17.6, and 8.4 % higher L-isoleucine production than the original strain, respectively. Both YILWpXMJ19thrABC and YILWΔalaT excreted lower concentrations of L-lysine, L-alanine, and L-valine. YILWΔalaTpXMJ19thrABC exhibited a cumulative reduction of these by-products excretion, which indicated that thrABC overexpression combined with alaT deletion resulted in the metabolic flux redistribution from 2-ketobutyrate and pyruvate to L-isoleucine synthesis, and decreased the fluxes to by-products synthesis accordingly.

Mechanism of Cellular Oxidation Stress Induced by Asymmetric Dimethylarginine

The mechanism by which asymmetric dimethylarginine (ADMA) induces vascular oxidative stress is not well understood. In this study, we utilized human umbilical vein endothelial cells (HUVEC) to examine the roles of ADMA cellular transport and the uncoupling of endothelial nitric oxide synthase (eNOS) in contributing to this phenomenon. Dihydroethidium (DHE) fluorescence was used as an index of oxidative stress. Whole cells and their isolated membrane fractions exhibited measureable increased DHE fluorescence at ADMA concentrations greater than 10 μM. ADMA-induced DHE fluorescence was inhibited by co-incubation with L-lysine, tetrahydrobiopterin (BH4), or L-nitroarginine methyl ester (L-NAME). Oxidative stress induced in these cells by angiotensin II (Ang II) were unaffected by the same concentrations of L-lysine, L-NAME and BH4. ADMA-induced reduction in cellular nitrite or nitrite/nitrate production was reversed in the presence of increasing concentrations of BH4. These results suggest that ADMA-induced DHE fluorescence involves the participation of both the cationic transport system in the cellular membrane and eNOS instead of the Ang II-NADPH oxidase pathway.

Effect of dietary l-lysine levels on growth, feed conversion, lysine retention efficiency and haematological indices of Heteropneustes fossilis (Bloch) fry

Effect of varying dietary lysine levels on growth, feed conversion, nutrient retention, lysine retention efficiency and haematological indices of Heteropneustes fossilis fry (2.97 ± 0.11 cm; 4.78 ± 0.31 g) was studied by conducting a 12-week feeding trial. Isonitrogenous (450 g kg−1 CP) and isocaloric (17.97 kJ g−1 GE) amino acid test diets with graded concentrations of l-lysine (18, 20, 22, 24, 26, 28 g kg−1 dry diet) were fed to triplicate groups of fish to apparent satiation twice daily at 17 and 17:30 h. Maximum thermal growth coefficient (TGC, 0.82), best feed conversion ratio (FCR, 1.28) highest protein retention efficiency (PRE, 36%), energy retention efficiency (ERE, 79%) and lysine retention efficiency (LRE, 75%) were noted at 24 g kg−1 lysine of dry diet. Body protein was also found to be in line with growth data and peaked at 24 g kg−1 lysine of dry diet. Similarly, superior somatic and haematological indices were exhibited by the groups fed dietary lysine at 24 g kg−1 of the dry diet. However, exponential analysis of dietary lysine intake against TGC, lysine retention and protein retention indicated that inclusion of dietary lysine in the range of 13.24–14.14 g kg−1 dry diet, corresponding to 29.42–31.42 g kg−1 dietary protein, is essential for faster growth of this fish.

Functional relationship between cationic amino acid transporters and β-defensins: Implications for dry skin diseases and the dry eye

The ocular surface, constantly exposed to environmental pathogens, is particularly vulnerable to infection. Hence an advanced immune defence system is essential to protect the eye from microbial attack. Antimicrobial peptides, such as β-defensins, are essential components of the innate immune system and are the first line of defence against invaders of the eye. High concentrations of l-arginine and l-lysine are necessary for the expression of β-defensins. These are supplied by epithelial cells in inflammatory processes. The limiting factor for initiation of β-defensin production is the transport of l-arginine and l-lysine into the cell. This transport is performed to 80% by only one transporter system in the human, the y +-transporter. This group of proteins exclusively transports the cationic amino acids l-arginine, l-lysine and l-ornithine and is also known under the term cationic amino acid transporter proteins (CAT-proteins). Various infections associated with l-arginine deficiency (for example psoriasis, keratoconjuctivitis sicca) are also associated with an increase in β-defensin production. For the first time, preliminary work has shown the expression of human CATs in ocular surface epithelia and tissues of the lacrimal apparatus indicating their relevance for diseases of the ocular surface. In this review, we summarize current knowledge on the human CATs that appear to be integrated in causal regulation cascades of β-defensins, thereby offering novel concepts for therapeutic perspectives.

The Chemistry of Escapin: Identification and Quantification of the Components in the Complex Mixture Generated by an L‐Amino Acid Oxidase in the Defensive Secretion of the Sea Snail Aplysia californica

Escapin is an L-amino acid oxidase in the ink of a marine snail, the sea hare Aplysia californica, which oxidizes L-lysine (1) to produce a mixture of chemicals which is antipredatory and antimicrobial. The goal of our study was to determine the identity and relative abundance of the constituents of this mixture, using molecules generated enzymatically with escapin and also using products of organic syntheses. We examined this mixture under the natural range of pH values for ink-from approximately 5 at full strength to approximately 8 when fully diluted in sea water. The enzymatic reaction likely forms an equilibrium mixture containing the linear form alpha-keto-epsilon-aminocaproic acid (2), the cyclic imine Delta(1)-piperidine-2-carboxylic acid (3), the cyclic enamine Delta(2)-piperidine-2-carboxylic acid (4), possibly the linear enol 6-amino-2-hydroxy-hex-2-enoic acid (7), the alpha-dihydroxy acid 6-amino-2,2-dihydroxy-hexanoic acid (8), and the cyclic aminol 2-hydroxy-piperidine-2-carboxylic acid (9). Using NMR and mass spectroscopy, we show that 3 is the major component of this enzymatic product at any pH, but at more basic conditions, the equilibrium shifts to produce relatively more 4, and at acidic conditions, the equilibrium shifts to produce relatively more 2, 7, and/or 9. Studies of escapin's enzyme kinetics demonstrate that because of the high concentrations of escapin and L-lysine in the ink secretion, millimolar concentrations of 3, H(2)O(2), and ammonia are produced, and also lower concentrations of 2, 4, 7, and 9 as a result. We also show that reactions of this mixture with H(2)O(2) produce delta-aminovaleric acid (5) and delta-valerolactam (6), with 6 being the dominant component under the naturally acidic conditions of ink. Thus, the product of escapin's action on L-lysine contains an equilibrium mixture that is more complex than previously known for any L-amino acid oxidase.

Mechanism of action of θ-amino acids on plasminogen activation and fibrinolysis induced by staphylokinase

Stimulation of Lys-plasminogen (Lys-Pg) and Glu-plasminogen (Glu-Pg) activation under the action of staphylokinase and Glu-Pg activation under the action of preformed plasmin-staphylokinase activator complex (Pm-STA) by low concentrations and inhibition by high concentrations of omega-amino acids (>90-140 mM) were found. Maximal stimulation of the activation was observed at concentrations of L-lysine, 6-aminohexanoic acid (6-AHA), and trans-(4-aminomethyl)cyclohexanecarboxylic acid 8.0, 2.0, and 0.8 mM, respectively. In contrast, the Lys-Pg activation rate by Pm-STA complex sharply decreased when concentrations of omega-amino acids exceeded the above-mentioned values. It was found that formation of Pm-STA complex from a mixture of equimolar concentrations of staphylokinase and Glu-Pg or Lys-Pg is stimulated by low concentrations (maximal at 10 mM) of 6-AHA. Negligible increase in the specific activities of plasmin and Pm-STA complex was detected at higher concentrations of 6-AHA (to maximal at 70 and 50 mM, respectively). Inhibitory effects of omega-amino acids on the rate of fibrinolysis induced by staphylokinase, Pm-STA complex, and plasmin were compared. It was found that inhibition of staphylokinase-induced fibrinolysis by omega-amino acids includes blocking of the reactions of Pm-STA complex formation, plasminogen activation by this complex, and lysis of fibrin by forming plasmin as a result of displacement of plasminogen and plasmin from the fibrin surface. Thus, the slow stage of Pm-STA complex formation plays an important role in the mechanism of action of omega-amino acids on Glu-Pg activation and fibrinolysis induced by staphylokinase. In addition to alpha-->beta change of Glu-Pg conformation, stimulation of Pm-STA complex formation leads to increase in Glu-Pg activation rate in the presence of low concentrations of omega-amino acids. Inhibition of Pm-STA complex formation on fibrin surface by omega-amino acids is responsible for appearance of long lag phases on curves of fibrinolysis induced by staphylokinase.

Bioefficacy of L-lysine·H2SO4 relative to L-lysine·HCl in broiler chickens, estimated by slope-ratio model

1. A broiler experiment was conducted to assess the effectiveness of L-lysine·H2SO4 relative to L-lysine·HCl. Four concentrations of L-lysine·H2SO4 and L-lysine·HCl (0·9, 1·8, 2·7 and 3·6 g/kg diet) were each added to a basal diet that met the nutrient requirements of broilers except for lysine. 2. Birds responded significantly to the supplements in daily gain, feed intake, feed conversion efficiency, nitrogen retention and plasma urea nitrogen during each period (d 4 to 21, d 22 to 42 and d 4 to 42). 3. Regression analysis showed that the bioefficacy of L-lysine·H2SO4 relative to L-lysine·HCl was 0·93, 0·86 and 0·95 for daily gain, feed conversion efficiency and nitrogen retention, respectively, during the starter period (d 4 to 21), and was 1·01, 1·36 and 1·06, respectively, during the grower period (d 22 to 42). It was 0·99, 1·07 and 1·03, respectively, for the overall period (d 4 to 42), when the bioefficacy of L-lysine·HCl was set at 1·0. 4. The bioefficacy of L-lysine·H2SO4 differed with different response criteria. The average bioavailability of L-lysine·H2SO4 relative to L-lysine·HCl was 1·03 on an equimolar basis in the present study. In conclusion, L-lysine·H2SO4 and L-lysine·HCl are equally efficacious to broiler chickens.

Effects of corn source and increasing lysine content on growth performance in swine (2005)

Three studies were conducted to evaluate the effect on growth performance when NutriDense (ND) corn is used in conjunction with increasing amounts of L-lysine, threonine, and methionine. NutriDense corn is a nutritionally enhanced product containing a stacked set of traits to provide greater nutrient density than is provided by conventional yellow dent corn (YD). In Experiment 1, a total of 320 pigs (initial 40.2 lb) were blocked by weight to one of eight dietary treatments. Pigs were fed corn-soybean meal diets with either YD or ND corn and with 3, 5, 7, or 9 lb of crystalline L-lysine per ton of complete feed. Rates of methionine and threonine to lysine were balanced across all dietary treatments by the addition of DL-methionine and L threonine. There were no corn-source × L-lysine amount interactions in this experiment. Increasing L-lysine decreased ADG (linear, P<0.01) and worsened F/G (linear, P<0.01; quadratic, P<0.10). There was no effect (P>0.23) of corn source on ADG, ADFI, or final weight, but pigs fed diets with ND corn had improved (P<0.05) feed efficiency. Experiments 2 and 3 were conducted at a commercial swine research facility in southwestern Minnesota. In Experiment 2, a total of 1,189 gilts (initially 87.7 lb) were used; in Experiment 3, a total of 1,136 gilts (initially 187.3 lb) were blocked by weight in a 28-d growth assay. In both experiments, there were six dietary treatments that included either YD or ND corn and increasing amounts of Llysine HCl (3, 6, and 9 lb/ton). In Experiment 2, there were no corn-source × L-lysine content interactions. Increasing dietary L-lysine HCl decreased ADG (linear, P<0.01) and worsened F/G (linear, P<0.01; quadratic, P<0.08). Feeding pigs diets with ND corn increased (P<0.07) ADG and improved (P<0.01) feed efficiency. In Experiment 3, there was a corn source × L-lysine content interaction (P<0.02) for ADG and F/G. This interaction occurred because there was a greater decrease in ADG for pigs fed diets with YD corn and increasing Llysine, compared with ADG of pigs fed diets with ND corn. No other interactions were observed (P>0.53). Increasing L-lysine decreased ADG (quadratic, P<0.01) and worsened F/G (quadratic, P<0.01). Feeding pigs diets with ND corn increased (P<0.01) ADG and improved (P<0.01) F/G, but had no effect on ADFI. The use of ND corn in swine diets will reduce the amount of threonine and methionine needed when high concentrations of crystalline L-lysine are used in corn-soybean meal diets. Also, because ND corn has 34% more tryptophan than typical YD corn does, higher concentrations of L-lysine, in conjunction with threonine and methionine, can be used before tryptophan becomes the dietary limiting amino acid. These studies indicate that the use of ND corn can reduce the need for threonine and methionine supplementation when supplementing with more than 0.15% Llysine HCl.; Swine Day, 2005, Kansas State University, Manhattan, KS, 2005