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Amino acids containing L-Arginine (Arg), L-Lysine (Lys) and L-Histidine (His) are recognized to increase the solubility of myosin at low ionic strength, but there is a difference in the researchers’ views on their effects on the secondary structure of myosin. To elucidate which method is relatively appropriate for the determination of secondary structures of myosin added with Arg, Lys or His, Circular dichroism (CD) spectra and Raman spectroscopy were carried out respectively. Raman spectroscopy was more suitable than CD method for determination of the secondary structures of myosin added with His, while CD spectra was more accurate for the myosin samples added with Lys and the adequate concentration of Lys should be under 10 mM. Both CD and Raman methods could be applied to myosin added with Arg, however, the latter was recommended and the adequate additive content of Arg in CD method should be less than 10 mM.

KCNE β-subunits play critical roles in modulating cardiac voltage-gated potassium channels. Among them, KCNE1 associates with KCNQ1 channel to confer a slow-activated IKs current, while KCNE2 functions as a dominant negative modulator to suppress the current amplitude of KCNQ1. Any anomaly in these channels will lead to serious myocardial diseases, such as the long QT syndrome (LQTS). Trafficking defects of KCNE1 have been reported to account for the pathogenesis of LQT5. However, the molecular mechanisms underlying KCNE forward trafficking remain elusive. Here, we describe an arginine/lysine-based motif ([R/K](S)[R/K][R/K]) in the proximal C-terminus regulating the endoplasmic reticulum (ER) export of KCNE1 and KCNE2 in HEK293 cells. Notably, this motif is highly conserved in the KCNE family. Our results indicate that the forward trafficking of KCNE2 controlled by the motif (KSKR) is essential for suppressing the cell surface expression and current amplitude of KCNQ1. Unlike KCNE2, the motif (RSKK) in KCNE1 plays important roles in modulating the gating of KCNQ1 in addition to mediating the ER export of KCNE1. Furthermore, truncations of the C-terminus did not reduce the apparent affinity of KCNE2 for KCNQ1, demonstrating that the rigid C-terminus of KCNE2 may not physically interact with KCNQ1. In contrast, the KCNE1 C-terminus is critical for its interaction with KCNQ1. These results contribute to the understanding of the mechanisms of KCNE1 and KCNE2 membrane targeting and how they coassemble with KCNQ1 to regulate the channels activity.

Interactions between heparan sulfate proteoglycans and the partner proteins regulate many aspects of cell functions, however, their binding properties are still equivocal. Developed eight years ago was a method for selective labelling of lysine residues in the heparin binding sites of Fibroblast Growth Factors (FGFs). The labelling of arginine residues is far more challenging, due to the multiple reaction products between a dicarbonyl and a guanidino group.

Additives are widely used to suppress aggregation of therapeutic proteins. However, the molecular mechanisms of effect of additives to stabilize proteins are still unclear. To understand this, we herein perform molecular dynamics simulations of lysozyme in the presence of three commonly used additives: arginine, lysine, and guanidine. These additives have different effects on stability of proteins and have different structures with some similarities; arginine and lysine have aliphatic side chain, while arginine has a guanidinium group. We analyze atomic contact frequencies to study the interactions of the additives with individual residues of lysozyme. Contact coefficient, quantified from contact frequencies, is helpful in analyzing the interactions with the guanidine groups as well as aliphatic side chains of arginine and lysine. Strong preference for contacts to the additives (over water) is seen for the acidic followed by polar and the aromatic residues. Further analysis suggests that the hydration layer around the protein surface is depleted more in the presence of arginine, followed by lysine and guanidine. Molecular dynamics simulations also reveal that the internal dynamics of protein, as indicated by the lifetimes of the hydrogen bonds within the protein, changes depending on the additives. Particularly, we note that the side-chain hydrogen-bonding patterns within the protein differ with the additives, with several side-chain hydrogen bonds missing in the presence of guanidine. These results collectively indicate that the aliphatic chain of arginine and lysine plays a critical role in the stabilization of the protein.

The study was conducted to determine the optimum dietary concentration of arginine relative to lysine on the basis of the performance, carcass traits and blood characteristics of 1–35-day-old broilers using a randomised complete block design. One-day-old broilers (n = 1200) were allocated to five dietary treatment groups receiving different arginine:lysine (Arg:Lys) ratios, where the proportion of Arg was progressively increased by increments of 10%, and the concentration of lysine was kept constant; the final ratios were 0.85, 0.95, 1.05, 1.16 and 1.26. Each diet treatment was composed of eight replicates (4 males and 4 females), with 30 chickens each replicate. All broilers were fed in three phases, namely starter, grower and finisher, at 1–10, 11–24 and 25–35 days of age respectively. An increase in the Arg:Lys ratio in the diet from 0.85 to 1.26 linearly (P < 0.001) increased bodyweight gain by 7% and improved feed conversion ratio by 6%. Feed intake and mortality were not significantly (P > 0.05) different among the treatments. Increasing the Arg:Lys ratio in the diet linearly (P < 0.0001) and quadratically (P < 0.05) improved the carcass yield and relative chilled carcass weight respectively. The percentages of breast meat and creatinine and insulin-like growth factor-1 concentrations also linearly (P < 0.0001) increased by 5.5%, 23.0% and 18.0% respectively, with an increasing dietary Arg:Lys ratio. The results of the present study indicated that the highest dietary Arg:Lys ratio (1.26) improved bodyweight gain, feed conversion ratio, breast meat, creatinine and insulin-like growth factor-1. However, the optimum dietary Arg:Lys ratio to improve carcass yield and weight gain in the grower phase (Days 11–24 of age) was at 1.05.

The effect of Arg:Lys, Met source, and time of exposure to heat stress on growth and body protein accretion was tested in acutely heat-stressed (AHS) or chronically heat-stressed (CHS) broilers. Ross 308 1-day-old chickens were raised under normal brooding conditions from 1 to 25 d of age and were then suddenly moved to 32 degrees C (AHS), whereas another group was kept at constant high temperatures throughout the grow-out period (32 degrees C; CHS). From 26 to 33 d of age, both groups were therefore at 32.8 +/- 1.0 degree C. Two rooms were used per environmental treatment. A basal diet deficient in TSAA was supplemented with L-Arg monohydrochloride to achieve Arg:Lys ratios of 0.95 and 1.40. Diets were supplemented with either L-Met, 2-hydroxy-4-(methylthio) butanoic acid (HMB), or DL-Met (DLM) to a level of TSAA 5% lower than requirements. Each Arg:Lys and Met source combination was diluted with a N-free diet to achieve graded levels of CP (0.0, 3.5, 7.0, 10.5, 14.0, and 17.5% CP) and fed to 18 replicates of 3 chickens (3 replicates per level). Treatment effects were obtained by the slope-ratio technique using average daily BW gain and body CP deposition as dependent variables and protein intake as the independent variable. Protein utilization remained unaffected by Met source when fed at high Arg:Lys for birds under AHS and CHS (P0.05). However, lower protein utilization was observed in birds fed L-Met in low Arg:Lys compared with those fed DLM (P0.05). Birds fed HMB at low Arg:Lys utilized dietary protein better than those fed L-Met only under CHS conditions (P0.05). Protein utilization for birds fed HMB was similar to that of birds fed DLM in all instances. It was concluded that Arg:Lys, Met source, and time of exposure to heat stress affected protein utilization in hyperthermic birds.

In two experiments, the effects of arginine:lysine, NaHCO3 and methionine source on performance and amino acid digestion of heat-stressed broilers were studied. In exp. 1, corn/soy diets with argine:lysine (Arg:Lys) of 1.10, 1.25 and 1.40 were fed from 21 to 42 d. Diets were supplemented with 2-hydroxy-4-(methylthio)-butanoic acid (HMB) or DL-Methionine (DLM) with NaHCO3 at 0 or 1.04%. Ten replicates per treatment of four birds per cage were maintained at 31.7 ± 0.9°C. From 21 to 28 d weight gain (BWG), feed consumption and feed-to-gain (FCR) were unaffected by diet treatment. Methionine source did not influence bird performance (P > 0.05). However, from 35 to 42 d, when diets were supplemented with NaHCO3, BWG and FCR of birds fed DLM were compromised when offered diets with Arg:Lys at 1.40. In diets devoid of NaHCO3, increasing Arg:Lys to 1.25 impaired BWG and FCR for broilers fed DLM, although effects disappeared when more Arg was used. Performance of birds on HMB was mostly unaffected by Arg:Lys or NaHCO3 except when fed diets void of NaHCO3 with Arg:Lys of 1.40, when FCR was impaired. In exp. 2, broilers were maintained at thermoneutrality (TN) reaching 20°C at 33 d. Other birds were at 31°C throughout, representing chronic heat stress (CHS), while a third group changed suddenly from 20 to 31°C at 25 d representing acute heat stress (AHS). Birds within each environment were housed in one of two rooms with eight replicates of four birds per treatment. At 25 d, birds were fed Arg:Lys of 0.95 or 1.40 with DLM supplemented at requirement. Birds fed Arg:Lys of 1.40 were also offered diets with synthetic L-methionine (L-Met). Adding L-Met to high Arg diets during CHS significantly depressed ileal digestibility of all amino acids (P < 0.05). It is concluded that chronic heat stress can affect the digestibility of amino acids, and that this effect may impact performance. Key words: Broilers, methionine, arginine, heat stress, digestibility, sodium bicarbonate

The nutritional antagonism of arginine (Arg) and lysine (Lys) was first identified and investigated in the 1950′s and 1960′s. The results of this early research suggest the optimum Arg:Lys ratio to...

There has been much controversy concerning the relative efficacies of equimolar quantities of DL-methionine (DLM) and 2-hydroxy-4-(methylthio) butanoic acid (HMB). Inspection of published literature suggests that the dietary Arginine:Lysine (Arg:Lys) ratio could be involved, especially during heat stress. In Experiment 1, conducted at 32°C, increasing supplemental HMB from 0.16 to .32% in a diet with an Arg:Lys ratio of 1.36 produced a significant increase in body weight gain (BWG) from 21 to 38 days. However, increasing DLM in an equimolar manner did not. Feed intake (FI) was better for the HMB birds. In Experiment 2, where diets with an Arg:Lys ratio of 1.03, 1.20, or 1.34 were fed at 32°C, birds fed HMB gave significantly improved BWG and FCR at a higher FI between 42 and 48 days compared to birds fed DLM. The FI of birds fed DLM decreased more rapidly than the FI birds fed HMB as dietary Arg:Lys ration increased. Therefore, a knowledge of Arg:Lys ratio appears to be required to optimize the methionine activity source.

The objective of this study was to evaluate the influence of methionine sources (DL-methionine 99% powder (DLM) or methionine hydroxy analog liquid 88% (HMTBA)), arginine:lysine (Arg:Lys) ratio and sodium chloride (NaCl) content in the diet of broilers on their performance, carcass yield, serum biochemistry, duodenal mucosal morphology, and immune response. Birds were kept under high temperature conditions during the grower phase and were inoculated or not with an antigen. The use of HMTBA promoted better live performance and carcass yield than the use of DLM. Diets with 1.05 Arg:Lys ratio resulted in better live performance, higher carcass and breast meat yields, longer villi, shallower crypts, and stronger immune response when broilers were challenged than the 1.40 ratio. The dietary supplementation of 6.0 g NaCl/kg promoted better growth performance and carcass weight than 2.0 g NaCl/kg. There was no influence of the different methionine sources or NaCl concentrations on any evaluated intestinal morphology parameter or immune response, nor of any interactions between these sources of variation.

A series of ω‐bromo‐2(S)‐methyl acids has been synthesized as precursors of novel arginine (Arg), lysine (Lys), and mercapto analogues. These intermediates contain α‐methyl groups and are designed to mask the N‐terminal amine when incorporated in pharmaceutically relevant peptides.

Summary l -Arginine is the endogenous source of nitric oxide in the endothelial cells of blood vessels. In thoracic aorta from Watanabe heritable hyperlipidaemic (WHHL) rabbits, the l -arginine/lysine and l -arginine/aspartic acid ratios were reduced in comparison to New Zealand rabbit aorta. This result indicates that a variation in aortic arginine/lysine or arginine/aspartic acid ratios could be related to the hyperlipidaemic status.

The content of lysine and arginine residues in a number of A-B type protein toxins has been examined. It is found that the A subunit, or its equivalent, often shows a strong bias in the type of basic amino acid residue used tending towards nearly exclusive use of either arginine or lysine rather than use of both, whereas the B subunit or its equivalent shows no such bias. Although arginine codons are GC-rich and lysine codons are AT-rich, the content of GC and AT in the genes coding for the toxins does not adequately explain this bias. Other explanations are discussed, including the possibility that the bias is linked to catalytic function or membrane interaction. Understanding this bias may yield valuable insights into toxin structure and function. Furthermore, identification of bias in sequences may be a useful tool for identifying new toxins and their domains.

Synopsis Pullets were fed on diets containing various concentrations of lysine and arginine from 7 to 18 or 20 weeks. Thereafter a conventional layers' diet was fed and egg productivity measured—in the first two experiments for ten, and the third for six 28‐d periods. Pullets were also fed on a standard growers' type diet on a “skip‐a‐day” or on a 20% restriction basis in the third study. Growth and age at sexual maturation were directly related to the lysine content of the diet and to a lesser extent to the arginine content. Pullets fed on diets with the lower concentrations of lysine and arginine required less food during the growing period and matured later than those fed on a complete diet ad libitum. They also laid more eggs and required less food to produce a dozen eggs. Higher egg production was obtained in the third experiment with low concentrations of lysine and arginine than with the “skip‐a‐day” or the restricted feeding programmes. Pullets fed on the normal grower diet ad libitum produced the...

1. 1. The renal reabsorption characteristics of arginine, lysine and ornithine have been studied in the young cockerel by renal clearance methods. 2. 2. Increasing the filtered load of any one of these amino acids by infusion caused a decrease in the efficiency of renal reabsorption of that amino acid and decreases in the efficiencies of reabsorption of the other two amino acids. 3. 3. It is probable that the cationic amino acids utilize a common transport system for renal reabsorption in the fowl.

Arginine-, lysine- and leucine-vasopressin, injected i. v. into hydrated rats or dogs caused different patterns of response in that urine osmolality fell much more slowly after the maximum increase following arginine-vasopressin, than after the other two preparations. Using 3 different parameters for antidiuretic response, arginine-vasopressin was somewhat more potent than leucine-vasopressin in both rats and dogs, considerably more potent than lysine-vasopressin in rats, and much more so in dogs.

Crossbred growing-finishing pigs (112 barrows, 48 gilts) were used to determine the effect of reducing excess dietary arginine, through feedstuff variation, on performance, carcass composition and plasma amino acid concentrations. Diets contained five, four, three or two times the NRC requirement for arginine. Lysine in all diets was formulated to be equal to NRC requirements, and all diets contained at least 100% of the NRC recommendations for all other essential amino acids. Initial weight, final weight and days on test for the grower phase were 26.7 kg, 44.2 kg and 28 d, respectively. Weight gain and gain/feed were not different among treatments but feed intake showed a quadratic response during the grower phase, being highest at four times the NRC requirement for arginine. Initial weight, final weight and days on test for the finisher phase were 44.2 kg, 96.9 kg and 67 d, respectively. Weight gain during the finisher phase and for the total experiment exhibited a quadratic response, being highest for the pigs fed the intermediate arginine levels. Gain/feed for the finisher phase followed the same trend as weight gain. Feed intakes for the finisher phase and total experiment were not different among treatments. Carcass data were collected on all barrows. There were no differences in hot carcass weight or adjusted average backfat among treatments. Loin eye area and percentage of lean decreased linearly as arginine level decreased in the diet. Plasma urea, arginine and orthinine concentrations decreased linearly with decreasing dietary arginine. Plasma lysine exhibited both a quadratic and a cubic response. The data indicate that reducing excess dietary arginine had little effect on performance or carcass composition and no consistent effect on plasma lysine of growing-finishing swine.

Linear programmed diets designed to maximize the use of proteins and to minimize the use of free (1-) amino acids, and containing five dietary levels of each amino acid under test, were fed to weanling crossbred Carworth Farms No. 1 x Swiss mice in 14-day growth trials. Arginine dietary levels were 0.1, 0.2, 0.3, 0.4 and 0.7%; lysine: 0.2, 0.3, 0.4, 0.5 and 1.0%; tryptophan: 0.03, 0.07, 0.10, 0.13 and 0.17%; and phenylalanine: 0.10, 0.25, 0.40, 0.55 and 0.89%. Growth, feed consumption and regression-adjusted growth rates indicated the following minimum requirements: arginine less than 0.1% and probably zero, lysine 0.4%, tryptophan 0.1% and phenylalanine 0.4%. The AIN '76 reference diet was included in each amino acid test and resulted in superior growth and feed utilization. It was postulated that the greater content of free amino acids in our diets may have affected the efficiency of feed utilization adversely.

The steroidogenic and lipolytic activities of corticotrophin-(1–24)-tetracosapeptide and [Lys17,18]corticotrophin-(1-18)-octadecapeptide amide were compared with those of the corresponding analogues variously substituted in position 8 with homo-arginine, ornithine or lysine. Peptides substituted with homo-arginine showed a surprisingly high degree of biological activity; in all the tests performed, the loss of activity due to the substitution did not exceed a factor of 3 to 10, while peptides substituted with ornithine or lysine in position 8 only showed residual biological activity or none at all, depending on the test system used. The results reported demonstrated that the presence of a guanidino group (arginine or homo-arginine side chain) in position 8 of the ACTH peptide is essential for the preservation of a high level of biological activity; the length of the aliphatic chain carrying the guanidino group is of minor importance.

Previously we reported upon the results of arginine tolerance tests carried out in patients with amyotrophic lateral sclerosis (ALS) and hospitalized controls, both groups consisting of Caucasians living in the Kansas City area. 1 The levels of arginine were noted to be significantly lower in the patients than in the controls. Later, because of the extraordinarily high incidence of ALS among the Chamorros on Guam, and because there have been suggestions that the disease there might be different from the sporadic ALS encountered in Caucasian Americans, 2 the Metrecal arginine lysine tolerance test (MALTT) was also carried out both on Chamorro patients with ALS and hospitalized controls at the Guam Memorial Hospital, Agana, Guam in March 1964. The present paper describes and discusses our observations in these patients and controls. Material and Methods Patients and Controls.— A myelogram was performed on all patients whose disease had been diagnosed as ALS

SEROLOGICAL reagents have been used to identify allelic antigenic determinants of the peptide chains of immunoglobulins1. Several allotypic determinants of the heavy chains of human immunoglobulins have been identified2 and their distribution in human populations3 has been investigated. Only a few allotypic determinants of the K-type light chain of human immunoglobulins have been identified2 and one of these has been correlated with an amino-acid interchange in the invariable half of these peptide chains4–6. No homologous serological reagent has been available for the study of the L-type light chain.