Isomers Of Methionine Research Articles

D-Amino acids do no inhibit biofilm formation in Staphylococcus sp.

D-amino acids are responsible for cell wall re-modelling in Staphylococcus and are capable of inhibition and mature biofilm disassembly. Staphylococcus aureus and Staphylococcus epidermidis are recognised as recurrent nosocomial pathogens and a common cause of biofilm-associated infections. The combination of amino acids used in the study consisted of d- and l- isomers of tyrosine, methionine, tryptophan and phenylalanine. A semiquantitative microplate crystal violet assay was used to assess the effect of amino acids on biofilm development. Biofilm viability staining using fluorescent microscopy was performed to assess the effect of the amino acid mixtures on biofilm development on submerged surfaces. None of the amino acids when tested individually or as a mixture could reduce biofilm formation. However, at the highest concentration tested 25 mmol 1−1 equimolar D-amino acid mixture of tryptophan, phenylalanine, tyrosine and methionine caused a considerable biofilm inhibition in three Staphylococcus strains. Microscopy analysis showed that initial surface attachment remained unaffected at 25 mmol 1−1 mixture of d-amino acids but bacteria did not proceed to form mature biofilms. This suggests inhibition of protein synthesis or a lack of polysaccharide extracellular adhesin formation as no aggregates were observed. The reported bioactivity of D-amino acid on biofilm development and disassembly has been conflictual. It has been established that D-amino acids are incorporated in the bacterial cell wall suggesting they play a role in the complexity of biofilm lifecycle. However, our study indicates that they play no direct role in the inhibition of biofilm formation in Staphylococcus.

Molecules Involved in the Modulation of Rapid Cell Death in Xanthomonas

In earlier studies from this laboratory, Xanthomonas campestris pv. glycines was found to exhibit a nutrition stress-related postexponential rapid cell death (RCD). The RCD was exhibited in protein-rich media but not in starch or other minimal media. This RCD in X. campestris pv. glycines was found to display features similar to those of the programmed cell death (PCD) of eukaryotes. Results of the present study showed that the observed RCD in this organism is both positively and negatively regulated by small molecules. The amino acids glycine and l-alanine as well as the D isomers of valine, methionine, and threonine were found to induce the synthesis of an active caspase-3-like protein that was associated with the onset of RCD. Addition of pyruvate and citrate to the culture medium induced both the synthesis of active caspase-3-like protein and RCD. Higher levels of intracellular accumulation of pyruvate and citrate were also observed under conditions favoring RCD. On the other hand, dextrin and maltose, the hydrolytic products of starch, inhibited the synthesis of the caspase-3-like protein. Addition of glucose and cyclic AMP (cAMP) to the RCD-favoring medium prevented RCD. Glucose, cAMP, caffeine (a known inhibitor of a phosphodiesterase that breaks down cAMP), and forskolin (from the herb Coleus forskholii, known to activate the enzyme adenylate cyclase that forms cAMP) inhibited the caspase enzyme activity in vivo and consequently the RCD process. The addition of glucose and other inhibitors of RCD enhanced intracellular cAMP accumulation. This is the first report demonstrating the involvement of small molecules in the regulation of nutrition stress-related stationary-phase rapid cell death in X. campestris pv. glycines, which is programmed.

Stereochemistry of platinum complexes of the neutral amino acids allylglycine, S-methylcysteine, methionine, and corresponding sulfoxides

The stereochemistry—both configuration and conformation—of platinum complexes of the neutral amino acids allylglycine, methionine, S-methylcysteine and their sulfoxides, which all contain a potential metal binding site, X, has been investigated by 1-D and 2-D proton NMR spectroscopy, molecular mechanics calculations, and X-ray crystallography. The configuration of each diastereomer of square-planar complexes of general formula N, XPt(amino acidH)Cl 2 has been assigned for all five of the amino acids. Relative equilibrium concentrations in solution of isomers of allylglycine (2 S,4 S/2 S,4 R=2 R,4 R/2 R,4 S=5), S-methylcysteine (2 S, SR/2 S, SS=2), and methionine (2 S, SR/2 S, SS=1.1) have been determined. The vicinal proton–proton coupling constants and NOESY spectra employed to assign configurations to the isomers also permitted an assessment of chelate ring conformations for the coordinated ligands. X-ray structures of kinetically stable sulfoxide complexes were employed to assign their configurations, and subsequent decomposition of isolated methionine and S-methylcysteine sulfoxide chelate isomers isomers was used to assign the very similar proton spectra of the two diastereomers of the corresponding free sulfoxides amino acids. With the significant exception of the methionine sulfoxide complexes, molecular mechanics calculations generally yield low energy conformations and isomer ratios in qualitative agreement with the NMR and X-ray structure data for these platinum complexes.

Gas chromatographic and gas chromatographic—mass spectrometric studies on α-keto-γ-methylthiobutyric acid in urine following ingestion of optical isomers of methionine

Gas chromatographic and gas chromatographic—mass spectrometric studies on α-keto-γ-methylthiobutyric acid in urine following ingestion of optical isomers of methionine

Mitochondrial neutral amino acid transport: evidence for a carrier mediated mechanism.

Swelling of rat liver mitochondria induced by various neutral amino acids indicates that the L isomers of serine, alanine, methionine, valine, threonine, and leucine enter the mitochondrial matrix by a stereospecific process. Chemical modification of mitochondria with diazobenzenesulfonate or p-mercuribenzoate inhibited the rapid uptake of these compounds, as well as that of L-proline and glycine, to various extents. Diazobenzenesulfonate did not inhibit the transport of compounds that enter the mitochondrial matrix by simple diffusion, i.e., thiocyanate, nitrate, formate, bicarbonate, and acetate. Inhibition by p-mercuribenzoate was reversed by treatment with dithiothreitol. Inclusion of various neutral amino acids in the p-mercuribenzoate preincubation mixture substantially prevented inactivation of transport. Glycine, D- or L-serine, L-threonine, L-methionine, L-alanine, and L-valine all individually protected against the inactivation of glycine, L-serine, L-threonine, L-methionine, L-alanine, L-valine, L-proline, and beta-alanine transport, while L-proline, beta-alanine,

Studies on the uptake of radiolabeled DOPA, 5-HTP and tryptophan in rat tissuesin vivo: Effect of methionine, tryptophan and some keto acids

L-methionine (60 mg/kg or 10 mg/kg i.v.) with a tracer dose of dl-dopa significantly reduced the uptake of the latter in rat brain in vivo at 5 min. The rates of uptake and disappearance indicate that methionine possibly interferes with the influx as well as the efflux of label at the cell membrane. Similarly, l -tryptophan (80 mg/kg) depressed the uptake of DOPA in brain and pancreas. The administration of the d -isomers of methionine or tryptophan had no appreciable effects at the same dosages. Indole-3-pyruvic, 5-hydroxyindole acetic, 3-indole acetic, α-ketoglutaric, oxalacetic and pyruvic acids and the l - or d -isomers of ethionine had no effect on DOPA uptake. Methionine (60 mg/kg) had essentially no effect on the uptake of radiolabeled 5-HTP and tryptophan in brain in vivo . Among the several compounds listed above, only l -tryptophan exhibited some impairment on the uptake of labeled 5-HTP by brain in vivo .

Methionine Hydroxy Analogue and l-Methiomne in Broiler Diets

IT HAS been demonstrated by many workers (Bird and Mattingly, 1945; Clandinin et al., 1946; Saxena and McGinnis, 1952; German and Couch, 1950; and others) that the addition of methionine to broiler rations accelerated growth.Marett and Sunde (1966) found that full utilization of the isomers of methionine by the chick was dependent on the amino acid composition of the diets. The incorporation of methionine analogue did not produce as great a growth as did l-methionine. The results indicated that when mixtures of l-methionine and methionine analogue were supplemented to the diet of chicks at levels, equivalent to a 0.5% and 0.7% l-methionine, mixtures of about ⅔ l-methionine and ⅓ methionine analogue produced growth significantly better than with methionine analogue alone, ⅔ methionine analogue or ½ l-methionine mixtures. The above workers also found that when l-methionine was used at 0.8% level and compared with 0.96% methionine analogue (0.08% l-methionine equivalent), .

Relative Biological Value of dl-Methionine and Methionine Hydroxy Analogue in Chick Diets

ALMOST all of the data presented in the literature indicate equal utilization of the d- and l- isomers of methionine. This subject was recently reviewed by Marrett et al. (1964). The relative utilization of dl-methionine and Methionine Hydroxy Analogue (MHA) is much more controversial than that of the activity of the d- and l- forms of methionine. Bird (1952) found MHA to be equal to dl-methionine in supporting performance of chicks when fed on an equimolar basis. Gordon and Sizer (1955) reported that MHA had equal activity to l-methionine and was more active than dl or d-methionine when added on an equimolar basis to a sulfur amino acid deficient chick diet. Sullivan and Bird (1957) compared MHA and dl-methionine on an equimolar basis in 12 and 14% protein chick diets and found the analogue failed by a wide margin to support performance equivalent to dl-methionine. The addition of either urea…

The Effect of Other d Amino Acids on the Utilization of the Isomers of Methionine and its Hydroxy Analogue

INTRODUCTIONEXPERIMENTS have been conducted with chicks to determine the effects of methionine in purified amino acids diets when supplemented at different levels. Marrett et al. (1964) observed that the d-and l-isomers were equally utilized, when the rest of the diet was comprised of amino acids in their l-form. This was also found to be true in rats by Wretlind and Rose (1950). The hydroxy analogue of methionine (MA) has also been used as a substitute for methionine in practical and semi-purified diets (Bird, 1952; Gordon et al., 1954) containing about 20 percent protein. Sullivan and Bird (1957) reported that the use of dietary urea or diammonium citrate in a 12 percent protein diet improved chick growth over the addition of MA alone. The chicks also appeared to be able to utilize these compounds more readily in the MA supplemented diets than in dl-methionine supplemented diets. Comparisons by Gordon and…

The Effects of Different Isomers of Methionine on Growth of Chicks Fed Amino Acid Diets

BOTH d- and l-methionine are effectively utilized by rats (Wretlind and Rose, 1950), by humans (Rose et al., 1950, 1955), and by dogs (Stekol, 1935).Research carried out on chicks has brought about varying results. Grau and Almquist (1943) were among the earliest to demonstrate full utilization of both d-and l-isomers of methionine in chicks. Fell et al. (1959) used a semipurified diet in studies of the utilization of d- and l-amino acids. He showed that both isomers of methionine were effective in promoting growth. The d- forms of essential amino acids appear to be capable of serving as the major source of nitrogen for the chick’s manufacture of non-essential amino acids (Featherston et al., 1962). Full utilization of d-methionine was observed in adult roosters when all three forms were fed in nitrogen balance studies (Leveille et al., 1960). PROCEDUREBecause most of the work on amino acids with chicks…

The Effect of Feeding d-Methionine on the d-Amino Acid Oxidase Activity of Chick Tissues

IT HAS been reported by Gordon and Sizer (1955) that chickens do not utilize d-methionine as completely as l-methionine, and it was postulated that this is because d-methionine is metabolized primarily in the kidney tissue, and is partially lost by excretion. This view would appear to contradict the work of Fell et al. (1959) and Leveille et al. (1960) showing that the isomers of methionine are equivalent in the chicken as judged by both nutritional response and nitrogen retention, and of course by the original demonstration of the equal utilization of the optical isomers of methionine in the chick by Grau and Almquist (1943). Perhaps this apparent discrepancy is explicable in terms of an overloading of the capacity of the chick to transform d-amino acids to useful metabolites, similar to the effect demonstrated by Wretlind (1952) in rats. In that work, the isomers of methionine were found to be equivalent …

Growth-Modifying & Antimetabolite Effects of Amino Acids on Chrysanthemum

The question of the significance of free amino acids in soil or other cultural media has received attention in recent years in the fields of plant physiology (1, 3, 7, 13, 14, 15, 16, 17), soil microbiology (4, 5,11, 16) and soil chemistry (9, 10,12). Although it originally appeared that free amino acids were not to be found in soils, later reports (2, 10) indicated they could be extracted with aqueous and alcoholic solutions and determinations made with chromatographic methods. The quantities of amino acids found were quite variable. Amino acids added to soil were quite rapidly transformed, and usually undetectable in extracts made after 72 to 96 hours of incubation (11, 16). D-Amino acids and L-alloisoleucine appeared more resistant to change than other amino acids studied (16). Reports indicate that amino acids are absorbed by plants (3, 13, 14) and translocated with great speed in both phloem and xylem (8). Inhibitors of respiratory processes as well as low temperatures applied to fibrovascular tissue considerably retard translocation. The potential applications of research with the so-called unnatural (D-) isomers was pointed out (6, 17) in connection with the natural occurrences of Damino acids in antibiotics and parts of microorganisms. More recently, Ikawa, et al. (6) reported the finding of D-phenylalanine, D-allothreonine and D-alloisoleucine3 in peptido-lipids of bacterial origin. The demonstrated effectiveness of amino acids applied to root zones of plants in producing changes in morphology and growth rate (1, 13, 17) suggests a need for further research along these lines. Steinberg (13) found that frenching of tobacco could be simulated by furnishing leucine, isoleucine, or alloisoleucine to tobacco plants growing in sterile cultures. He reported that relatively large amounts of these amino acids were required under non-sterile conditions to produce frenching symptoms. Woltz and Jackson (15, 16, 17) found that symptoms of yellow strapleaf of chrysanthemum could be produced by small amounts of certain isomers of leucine, isoleucine, and alloisoleucine applied to the root zones of test plants growing in sterilized and nonsterilized media. Fifteen of twenty-two test plants developed syndromes similar to those of frenching and yellow strapleaf when a mixture of alloisoleucine and isoleucine isomers was applied to the root zones. Methionine applied to the root zones of chrysanthemum plants produced a physi-ological disorder given the name methionosis (17). Two of the twenty-two plants exhibited morphological changes due to methionine. A consideration of the information about the effects of externally applied amino acids on plant growth in the light of certain antimetabolite phenomena discussed by Woolley (18) led to the hypothesis that the growth-modifying effects observed might be largely antimetabolite effects. Natural (L-) amino acids could act as antimetabolites because of their structural similarity to other natural amino acids. Unnatural amino acids (D-form & others), due to their structural similarity to specific natural amino acids, could function as antimetabolites by being incorporated into peptides and blocking further synthesis due to the failure to completely fit the pattern of the natural amino acid. Experiments were planned to examine further the effects of various natural and synthetic amino acids on the growth rate and morphology of chrysanthemum plants. Chrysanthemum was selected for these studies because of its sensitivity to isomers of leucine, isoleucine, and methionine (17). The types of cultural media, amounts of amino acids applied, and timing of application relative to the development of new growth of axillary shoots were chosen to enhance growth effects so the effects might be recorded and evaluated. Interactions of related amino acids were explored to learn the degree to which the results would fit metabolite-antimetabolite relationships.

Effect of Vitamin B6 on the Growth of Rats Fed Diets Limiting in an Essential Amino Acid and on the Utilization of Isomers of Tryptophan, Methionine and Valine

Effect of Vitamin B6 on the Growth of Rats Fed Diets Limiting in an Essential Amino Acid and on the Utilization of Isomers of Tryptophan, Methionine and Valine

The Additive Effect of Glycine and other Amino Acids on the Induction of the L-Phase of Group A -Haemolytic Streptococci by Penicillin and D-Cycloserine

SUMMARY: The ability of glycine to induce L-phase of bacteria did not apply to group A β-haemolytic streptococci. In the presence of penicillin, glycine in a bacterial inhibitory concentration had a notably additive L-phase inducing property for streptococci. Reasons are given to support the view that this activity of glycine is limited to the induction of L-phase growth. A sharp increase in the yield of L-phase colonies was also observed when serine, threonine, methionine or alanine were tested under similar conditions. When the effectiveness of the racemate and both the isomers of these amino acids was compared, the d-isomer was the active substance in most cases. In one strain, the L-inducing and bacterial inhibitory action of the racemate and both isomers of methionine was tested simultaneously. The yield of L-phase colonies was found to be inversely proportional to the effect of the different stereoisomers on bacterial growth. d-Cycloserine had a weak L-inducing effect on group A streptococci, but the combined action of d-cycloserine and glycine or dl-serine was equal to that obtained with penicillin and the same amino acids. Propagation of these L-phase organisms was possible in the presence of 1% (w/v) glycine and within a narrow range of concentrations of d-cycloserine. The additive effect of the amino acids cited towards penicillin and d-cycloserine for the induction of L-phase structures can be explained by the antibiotic property of high concentrations of glycine and some of the d-amino acids.

Intestinal absorption of methionine and histidine by the chicken.

Intestinal absorption of methionine and histidine was studied in adult chickens having permanent Thiry-Vella fistulas. The l isomers of both amino acids were absorbed from the fistulas more rapidly than were the d isomers. At a concentration of 10–3 m, 2,4-dinitrophenol retarded absorption of l-methionine but not of the d form. The absorption of l-histidine was impaired in the presence of equimolar concentrations of either l- or d-methionine. Racemization of d-methionine during absorption could not be demonstrated. The l isomers of both methionine and histidine appear to be absorbed from the chicken intestine by a common specific transport mechanism, with d-methionine being able to participate in at least one stage of this mechanism.

The effect on growth and the toxicity of the two isomers of methionine.

Summary.This paper reports the results of growth tests on young white rats on diets adequate in other respects but containing varying concentrations of L‐ and D‐methionine.The following results were obtained:The concentration required for maintenance of the body‐weight was 0.10 % L‐methionine and 0.12 % D‐methionine in the diet.The effect of the D‐methionine on the growth was merely 76–84 per cent, of that of the L‐methionine.Maximal growth was obtained at a concentration of 0.25–1% L‐methionine and of 0.5C–.2% D‐methionine in the diet. D‐methionine seems to be less toxic than L‐methionine. A toxic effect on the growth (stagnation in weight) resulted at a concentration of 3.5% L‐methionine and of 5.4% D‐methionine in the diet.In default of methionine in the diet the animals had a poor appetite, which immediately improved on the addition of L‐ or D‐methionine. A maximal appetite was obtained with 0.125–1% L‐methionine or 0.125–4% D‐methionine. With higher concentrations a decrease in appetite would appear.