Methionine Solution Research Articles

EVALUATION OF A RIBOFLAVIN‐METHIONINE MIXTURE TO IMPROVE THE QUALITY OF AQUACULTURED CATFISH FILETS DURING THE CHILLING PROCESS

ABSTRACTAn optimized riboflavin‐methionine (RM) mixture with Escherichia coli (target organism) was evaluated for improving the quality of catfish filets during the chilling process. The RM mixture (pH 7.2) containing riboflavin (10μM), methionine (20 mM) and EDTA (1 mM) was photoactivated. E. coli cells grew in a medium containing l‐methionine when exposed to fluorescent light and grew in a RM mixture in the dark. However, the activated RM mixture injured and killed E. coli cells. As the concentration of riboflavin increased, the number of survivors decreased. The concentration of methionine did not significantly decrease the survival rate of E. coli. As pH increased, the number of killed and injured E. coli cells increased. The RM mixture injured and/or killed a low load of E. coli cells faster than a high load. Methionine solution or RM mixture added to the suspension in phosphate buffer (15 mM, pH 7.2) and photoactivated at 0 and 24C for 8h to simulate the chilling water significantly reduced the total coliform counts but not the standard plate counts. However, when the catfish filets were suspended in a RM mixture at 0 and 24C for 2h to simulate the chilling process, there was no reduction in standard plate or total coliform counts.

Glutamic Acid and 5-Aminolevulinic Acid May Function as Precursors of System II Ethylene in Ripening Tomato Fruit

The ethylene biosynthetic pathway has been established as methionine (MET) to S-adenosylmethionine to 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene, and this pathway has been labeled System I. Another pathway to ethylene may exist during synthesis of massive amounts of ethylene, and this system has been labeled System II. Our objective was to evaluate the efficacy of several compounds as possible precursors of System II ethylene in ripening tomato fruit tissue. Discs of `Rutgers' tomato pericarp tissue at the mature green, pink, and red ripe stages were incubated continuously in 10, 25, or 40 mm solutions of MET, ACC, 5-aminolevulinic acid (ALA), homocysteine, glutamic acid (GLU), alpha-ketoglutarate, or citrate buffer (control). The ethylene production rate at 8-hour intervals during a 32-hour incubation period and free and conjugated ACC content at the end of the incubation period were quantified. Fruit discs at the mature green stage treated with MET and ACC exhibited increased ethylene production and increased free ACC content. These results confirmed the role of MET and ACC as the predominant precursors of ethylene during the early stages of fruit development in tomato (System I). At the pink stage (System II); however, ALA increased ethylene production by 75% and free ACC content by 46% over the control, and MET increased ethylene by 27% and free ACC content by 57% over the control. At the red ripe stage, ALA caused a 35% increase and GLU caused a 31% increase in ethylene production over the control. These results suggest that ALA and GLU may be metabolized to ethylene via an unknown pathway during tomato fruit ripening (System II).

346 PRECURSORS OF SYSTEM II ETHYLENE SYNTHESIS IN SENESCING CARNATION PETALS

Methionine (MET) is considered the first committed precursor of ethylene (C2H4), and the pathway has been established as MET → S-adenosylmethionine (SAM) → 1-aminocyclopropane-1-carboxylic acid (ACC) → C2H4. It has been suggested that another pathway to C2H4 may exist, and this pathway has been labeled System II. Our objective was to evaluate several compounds as possible precursors of System II C2H4 production. `White Sim' carnations were placed continuously in 20 mM solutions of MET, ACC, δ-aminolevulinic acid, glutamic acid, α-ketoglutarate, or homocysteine. Deionized water was the control. C2H4 production from the entire flower was measured, and ACC in the basal portion of the petals was quantified. Flowers treated with ACC exhibited the greatest C2H4 production and accumulation of ACC. Homocysteine caused greater production of C2H4 and accumulated more ACC than MET and the other possible precursors. These results suggest that homocysteine may be involved in System II C2H4 production in senescing carnation petals.

Studies on the Ripening Acceleration of Vapor-Heat Treated Papaya.

Polygalacturonase (EC 3.2.1.15) (PGase) and invertase (EC 3.2.1.26) activities were compared with the untreated and the treated papaya thermally injured by vapor-heat treatment. PGase activity was higher in the normal fruits, and invertase activity was only slightly higher in the thermally injured fruits. The appearance of the thermally injured fruits might be caused by the effects of PGase. The rate of ethylene generation was studied by soaking the papaya in a methionine solution of ethylene precursor or an Ethrel (2-chloroethyl phosphonic acid) solution of an ethylene generating chemical. The results showed that the ethylene production rate was relatively higher in fruit treated with an Ethrel solution for both untreated and thermally injured fruits, and a quality improvement of the thermally injured fruit was suggested.

Products in light-mediated reactions of free methionine-riboflavin mixtures that are biocidal to microorganisms

Solutions of methionine (1 mM) plus riboflavin (26.6 μM) (MR mixture) in the presence of light are toxigenic to a wide spectrum of microorganisms. Agrobacterium tumefaciens and Verticillium dahliae are representative of these microorganisms and were used in this study. The biocidal activity of the MR mixture was significantly enhanced when aerated or supplemented with Cu2+ or Fe2+ ions; the increased toxicity suggested the involvement of the O2−-driven Haber–Weiss reaction, from which the associated production and reactivity of O2−, H2O2, and 1O2 may have contributed to the biocidal activity. Although the presence of EDTA did not lessen the toxicity of the MR mixture, the addition of butylated hydroxyanisole effectively quenched its biocidal activity. Supplementation of MR mixture with antioxidants like α-tocopherol and β-carotene also was effective in reducing its biocidal activity and suggested further that the production of the above-mentioned oxygen species was critical for a photodynamic toxigenic reaction. In addition to the involvement of oxygen derivatives, the role of various methionine photodegradation products in the biocidal reaction was also evaluated. Methional and acrolein were among the methionine-derived components that were toxic. The highest amounts of methional and acrolein detected in the MR reaction system during an 8-h period by HPLC were approximately 46.5 and 10.6 μM, respectively. However, to achieve the toxicity equivalent to that of the MR mixture, the production of more than 5 mM methional or 100 μM acrolein would be necessary. Thus, the overall toxicity of the MR mixture appeared to be associated with the generation of highly reactive oxygen radicals. Key words: methionine–riboflavin mixture, photodynamic toxicity, methional, acrolein, activated oxygen derivatives, Agrobacterium tumefaciens, Verticillium dahliae.

The palatability of amino acids and related compounds to rainbow trout, Salmo gairdneri Richardson

Using a behavioural assay, the palatability of urea, taurine, betaine and the 20 common amino acids (L‐isomers) to rainbow trout was determined. The trout responded positively only to aqueous solutions of leucine, isoleucine, proline, phenylalanine, tryptophan, methionine, glutamate, arginine, taurine and urea. Proline, the most effective compound, was active at 10 ‐4 m but not 10‐5m. Palatibility was not directly related to test solution pH; concentration and molecular structure apparently played a greater role. There is good, though not perfect, agreement between the behavioural results obtained here and published electrophysiological data on the palatal sensitivity of rainbow trout to these substances.

Carrier Protein-mediated Transport of Neutral Amino Acids into Mung Bean Mitochondria

The transport of neutral amino acids into mitochondria isolated from the hypocotyl of mung bean (Roxb.) was studied by the swelling technique. Isolated mitochondria swelled when added to an isosmotic solution of proline, serine, methionine, threonine, alanine, and glycine. The swelling was stereospecific in that it was faster in the l-amino acid than in the corresponding d-amino acid. Preincubation of the mitochondria with the sulfhydryl modifying reagents, p-mercuribenzoate and mersalyl, resulted in an inhibition of the swelling caused by proline, serine, threonine, and glycine. The swelling induced by alanine was inhibited only by mersalyl, whereas that by methionine was inhibited only by p-mercuribenzoate. In all cases, the inhibition caused by the sulfhydryl modifying reagents was readily reversible by the subsequent treatment of the mitochondria with dithiothreitol. N-Ethylmaleimide, another sulfhydryl-modifying reagent, did not cause any inhibition of the swelling. The findings indicate the existence of a protein mediated mechanism for the transport of neutral amino acids into plant mitochondria.

NUTRIFICATION OF DRY BEAN (Phaseolus vulgaris, L.) BY METHIONINE INFUSION

ABSTRACTThe technological conditions for the nutrification of beans by methionine infusion are described. The best conditions seem to be infusion for 1 hr with a 5% methionine solution at 50°C. By this procedure the methionine was raised from 1.2 to 24 g/100g of bean protein and the absorbed water was only 40% of the beans weight. The beans infused under these conditions, after drying, could be mixed 1:7 (w/w) with original beans and the mixture after cooking in the presence of the soaking water still contained 3% methionine on the protein basis. During soaking (prior to cooking) about one‐third of the infused methionine was diffused out in the remaining water. Therefore, elimination of the soaking water before cooking should be discouraged. Infusion with methionine raised the bean PER from 0.9 to 2.6 and the efficiency of a 10% bean protein diet from 9.4 to 26.6%. There was no difference in preference between the original and infused beans when the Directional Paired Comparison test was applied. However, when the Non Structured Scale test was used for the odor and taste of cooked beans there was no preference for the original beans when seasoning was used, whereas there was a significant difference at 5% probability level in favor of the original beans when the samples were cooked and tasted without seasoning.

Reactions of humic materials with methionine and arginine

The aerobic reactivity of humic matter was established for two reactions. Shaking pulverized litter or humic acid in solutions of methionine resulted in non-enzymatic formation of methionine sulfoxide. Shaking litter in a solution of arginine resulted in non-enzymatic loss of arginine (deamination and non-exchangeable fixation). Both forms of reactivity were stimulated at alkaline pH, were stronger when the material was “more phenolic”, were stronger when the material seemed to have been less involved in conversions in soil and were also found with acid-boiled humic acid. It is suggested that both forms of reactivity are caused by autoxidation of polyphenolic groups.

Material Balance and Additional Effect of Second Organic Solutes in the Radiolysis of Aqueous Methionine Solution

Material Balance and Additional Effect of Second Organic Solutes in the Radiolysis of Aqueous Methionine Solution

A Modification of the Mccarthy-Sullivan Method for the Assay of Methionine in Feather Meal Hydrolysates

A study has been underway for some time in this laboratory to investigate the feasibility of improving the methionine content of feather meal by microbial conversions. Since this study in part involved screening large numbers of cultures for methionine production, it was desirable to use a rapid and simple method for the assay of methionine in hydrolysates of fermented meal. Our interest turned to the method of McCarthy and Sullivan (1941), which is based on the production of a colored compound when methionine reacts with sodium nitroprusside under controlled conditions of temperature and pH. This test, however, failed to give reproduceable results in our hands when standard solutions of methionine were assayed. A number of modifications reported by Block and Boiling (1945), Korpaczy (19S4), Hiraoka (1955), and Mikulowska and Slowinski (1963) were also tested, but either were not reproduceable or failed to yield linear standard curves. However, a version described…

Physiological Action of Ethylene in Crop Plants : II. The role of endosperm in elongation of rice seedlings by ethylene

Generally ethylene inhibits the extention growth of plant. But we have reported that rice seedlings were elongated by application of Ethrel which id ethylene releasing agent. The experiments conducted to make clear the effect of Ethrel and ethylene on growth in rice seedlings. The results obtained were as follows ; 1. The stimulation of rice seedling elongation by Ethrel was closely related with the volume of endosperm of seeds. The elongation of seedlings was more stimulated in the seedlings with much volume of endosperm than in ones with less endosperm. 2. Untill the 2 nd leaf stage, the growth ef seedlings was stimulated by Ethrel application. After 3rd leaf stage, however, the growth was inhibited by Ethrel. It seems that promotion or inhibition of the growth of rice seedlings depended upon the growth stage which related to endosperm consumption. 3. The rice seedlings treated with Ethrel produced more ethylene than not-treated ones. Also ethylene production in seedlings was enhanced by application of methionine, as one of precursors of ethylene. Ethylene enhancement by Ethrel was more effective in dark than in light. On the other hand, ethylene production by methionine application was active in light. 4. In methionine solution rice seedlings produced more ethylene and carbondioxide than in water. The elongation was promoted in very early growth stage, especially in coleoptile, but inhibited in later stage by methionine application. In these experiments it became clear that elongation of rice seedlings by Ethrel had close relation with the volume of endosperm in seeds, and ethylene affected the elongation of seedlings. It was suggested that ethylene had the important function as stimulater of growth in rice seedlings at early growth stage.

Metabolism of S-adenosylmethionine in germinating pea seeds: Turnover and possible relationships between recycling of sulfur and transmethylation reactions

Tissue slices of pea cotyledons incubated with methionine labeled in the methyl group with 3H and 14C and with methionine 35S, rapidly incorporated radioactivity into S-adenosylmethionine. Such slices transferred to unlabeled methionine solutions showed a rapid turnover of labeled S-adenosylmethionine. Kinetic studies showed that sulfur-labeled and methyl-labeled S-adenosylmethionine had quite different rates of turnover. Such differences were related to the possible recycling of sulfur. Attempts to demonstrate direct methylation of S-adenosylhomocysteine in vitro were not successful. Experiments with S-adenosyl-8- 14C- l-homocysteine demonstrated conversion to adenosine- 14C and cell-free extracts catalyzed the synthesis of methionine from homocysteine, in the presence of S-adenosylmethionine, S-methylmethionine, or 5-methyltetrahydrofolate. It is concluded that in the metabolic turnover of S-adenosylmethionine the resulting S-adenosylhomocysteine is rapidly cleaved to give rise to adenosine and homocysteine. Homocysteine is then methylated by 5-methyltetrahydrofolate and the resulting methionine is utilized for regeneration of S-adenosylmethionine.

Radiation Chemical Reactions in Aqueous Solutions of Methionine and Its Peptides

In our preceding paper (1) the radiation chemical degradation of eleven dipeptides and tripeptides was studied in aqueous oxygenated and oxygen-free solutions. Analysis of the products formed and of their yields, together with previous work by Garrison and Weeks (2), permitted establishment of the mechanism of the major radiation chemical reactions. In oxygen-free solutions, the peptide bond remains practically intact, the major reactions being reductive deamination of the N-terminal amino acid in the peptide and recombination either of two peptide radicals or of one peptide molecule with its radical (on the methyl or methylene groups), yielding dimersthat is, neutral peptides-or of one deaminated peptide radical with the original peptide or its radical (on the same groups), yielding acidic peptides. In oxygenated solutions, peptide bond cleavage to the amide and carbonyl derivatives, oxidative deamination to the ketoacyl peptide, and cleavage of the intermediary imine radical of the N-terminal amino acid to the lower aldehyde and the free C-terminal amino acid are the main reactions, besides oxidation on the methyl and methylene groups. Some effects of the structure of the peptide have also been pointed out (1). In our present work similar investigations were carried out with methionine peptides to study the effect of the -SCH3 group in methionine on the radiolysis of the peptides. For this purpose it was necessary to reinvestigate the radiolysis of methionine under the experimental conditions employed. The radiolysis of methionine in aqueous solutions has been studied by our group (3-5) as well as by Kumta et al. (6, 7) and by Shimazu et al. (8). The latter authors studied the radiolysis of methio-

The effect of dl-methionine on the water intake of rats and their susceptibility to audiogenic seizures

1. The effect of dl-methionine on water intake and on the susceptibility of rats to audiogenic seizures was studied. Methionine was administered in drinking water or by intraperitoneal injection. In both cases water intake decreased but no loss of weight was observed. 2. A significant decrease in seizure susceptibility was observed in the 14th week by rats supplied with 0.1% methionine solution. A decrease that was not statistically significant was shown in the 10th week by rats supplied with 0.01 % methionine solution. 3. In rats that were given methionine intraperitoneally (500 mg/kg body weight) once a week, a change in the type of seizure was observed and there was an increase in the percentage of rats which did not have seizures. 4. There was considerable fluctuation with occurrence of spasms in rats receiving methionine. In the control group, spasms correlated with water intake. 5. Food consumption was not affected by the intake of methionine. 6. Rats receiving methionine eliminated 47 % of the water intake compared with 51 % eliminated in the control rats.

The collection and identification of thiols and disulphides

AbstractFollowing the evolution of sulphur compounds from cultures of marine organisms in methionine solution, the collection of thiols and disulphides in mercuric cyanide and mercuric chloride was studied. The subsequent conversion of the mercaptides and mercury complexes to 2,4‐dinitrophenyl sulphides was found to be possible by decomposing the mercury compounds with acid and collecting the mercaptan in caustic ethanol and then treatment with I‐chloro‐2,4‐dinitrobenzene. A method for the chromatography of the 2,4‐dinitrophenyl sulphides on paraffin‐impregnated paper was devised and studied.

Studies on the Effects of Amino-Acid on the Secretory Activity of the Gastric Peptic Cells and the Pancreatic Cells

10% solution or emulsion of amino acid, Alanine, Leucine, Methionine, Aspartic acid, Glutamic acid, Lysine, Arginine, Tyrosine, Histidine and Tryptophane, was injected into the stomach so that the effect of amino acid on the secretory activity of the gastric peptic cells and of the pancreatic cells might be proved.1. On the secretory activity of the gastric peptic cells, Methionine, Tyrosine, Histidine and Tryptophane are effective in various degree, the effects of the other amino acids are almost negligible. An effect can be seen without regard to pH value, or to number of amino-groups or acid-groups, or to the presence of S etc. of the solution or emulsion of amino acid.2. The effect on the peptic cells follows the discharge of the gastric hormone productin from the gastric surface cells, viz. the more active the amino acid in the secretion of productin the more promotive it is on the secretory function of the peptic cells.3. The most remarkable effect which exceeds others in degree can be seen in Histidine, an amino acid containing an imidazol group. The effect of Tyrosine and Tryptophane is low. This fact will be very interesting because an imidazol group has been previously proved to exist in the productin vacuoles of the gastric surface cells.4. On the production of zymogen granules in the pancreatic cells, the order was the same as that in the case of the discharge of productin, i. e. Histidine, Methionine, Tryptophane and Tyrosine.5. On the discharge of zymogen granules from the pancreatic cells, Tyrosine and Tryptophane are more effective than Histidine, and it is particularly noted that some of the amino acids which are almost negligible in their effect to the gastric peptic cells, display considerable activity in the discharge of zymogen granules. This activity can be detected in Alanine, Aspartic acid, Glutamic acid and Lysine. They may be active in the discharge of the duodenal hormone secretin though they are ineffectual in the discharge of the gastric hormone productin.

トリプトファンとパラジメチルアミノベンツアルデヒドの呈色の安定性に及ぼすアミノ酸その他化合物の影響

The Ehrlich reaction, the blue coloration formed by the reaction of tryptophan and p-dimethylaminobenzaldehyde in strong acid solution, is accelerated by heating the solution or by the addition of an oxidation agent but at the same time, the color becomes unstable and liable to be discolored. In this case, the addition of acid hydrolyzate of proteins effects stabilization of coloration and prolongation of the maintenance period of maximum coloration. In order to find substances which can stabilize this coloration, various amino acids were submitted to the test. It was found that methionine effected the greatest stabilization of the color, the color formed having been maintained over three months. This was followed by cystine, tyrosine, histidine, aspartic acid, and glutamic acid, which possessed a certain amount of stabilization effect, while the action of other amino acids was weaker. As for compounds other than amino acid, levulic acid possessed a strong action similar to that of methionine, while pyruvic acid and fructose also possessed a fairly strong action. These results indicated that compounds possessing a sulfur atom or a carbonyl group possessed strong action. Based on these results, 0.1-1.0% solution of methionine was adopted as the solvent for the coloration solution of tryptophan, in place of acid hydrolyzate of proteins.