Methionine solution preparation

The methionine nitrile (20 g) is dissolved in a solution prepared from 50 ml of aqueous 5N sodium hydroxide solution and 65 ml of ethanol. The solution is then refluxed for 24 hours ammonia is evolved. The solution is treated with activated carbon, filtered, acidified with glacial acetic acid (17 ml), chilled to -10°C and filtered to give crude product. This crude product is then slurried with a solution made up of 20 ml of water and 20 ml of methanol, filtered at -5° to -H0°C and dried to give dl-methionine as white platelets. 

Prepare 0.01 M solutions of leucine, methionine, valine, and lysine using a solvent that is 70% isopropyl alcohol and 30% water. Liquid food samples, such as fruit juice samples, can be used directly. Solid food samples must be soluble in the isopropyl alcohol-water solvent. Prepare solutions of solid samples as concentrated as possible. 

Hydrogen cyanide in pure form was prepared first in 1815 by Gay-Lussac. Earher, in 1782, Scheel prepared this compound in dilute solution. The most important apphcation of hydrogen cyanide is to produce methyl methacrylate for methacrylate resins and plastics. Other products made from hydrogen cyanide include potassium cyanide, sodium cyanide, adiponitrile, methionine, cyanuric chloride, cyanogen, nitrilotriacetic acid, and several triazine pesticides. The compound also is used in small amounts for extermination of rodents. 

Preparation and Irradiation of Solutions. Glycine, methionine, glycylglycine, and glycylmethionine were obtained from Nutritional Biochemicals Corp., Cleveland, Ohio, and used without further purification. All samples dissolved completely in deionized distilled water to give colorless solutions, except glycylmethionine which had a pale yellow color. Each solution was within 0.2 pH unit of its isoelectric pH (5.5 to 6.0). 

Methionine Sulfoxide Adsorption Check. S35-labeled methionine sulfoxide was prepared by oxidizing methionine-S35 with peroxide (6). Five microliters (ca. 20,000 counts per minute per microliter) of an aqueous solution of the sulfoxide was injected into each of 20 cockroaches. The first 10 were immediately immersed in hot 80% ethanol, and the remainder in hot 5% trichloroacetic acid to be homogenized and extracted. The extraction procedures were similar to those described above, except that precautions to prevent oxidation were not taken and the supernatant liquids, except for the acidified ethanol and ether washes, were not combined but were collected separately in 100-ml. volumetric flasks. The protein residues were hydrolyzed in 6N HC1 and, like the other fractions, were then diluted to 100 ml. with water for radiometric analysis. 

Aminocyclopropane carboxylic acid (6) has been detected in several plant tissues a procedure for preparing 6 from agricultural wastes, by extraction with a diluted solution of sulfosalicylic acid, has been described . 6 was established to be an intermediate product in ethylene biosynthesis " . Ethylene acts as a phytohormone which is involved in many metabolic processes in plants, e.g. in ripening, in stress situations or after wounding (see review and references cited therein). Natural 6 is formed from methionine via sulfonium salt (640) only S,S-(640) acted as a substrate for aminocyclopropanecarbo-xylate synthase, the S,R and R,R isomers of 640 were inactive as substrates . 6 can be... 

Describe preparation of lOO ml of a 10 M solution of L-methionine-S in which the amino acid has a specific activity of 1.5 X 10 DPM/ i.mole. Assume that you have available a 0.1 M solution of unlabeled L-methionine and a stock solution of L-methionine-S (30 mCi/mmole and 1 mCi/ml). 

Protease mutants were prepared, which showed higher catalytic activity for the enzymatic polymerization of amino acid esters in an aqueous DMF solution. The molecular weight greatly increased by using a subtilisin mutant (subtilisin 8350) derived from BPN (subtilisin from Bacillus amyloliquefa-ciens) via six site-specific mutants (Met 50 Phe, Gly 169 Ala, Asn 76 Asp, Gin 206 Cys, Tyr 217 Lys, and Asp 218 Ser) in the polymerization of L-methionine methyl ester in the aqueous DMF.240 Another mutant (subtilisin 8397), which is the same as 8350 without... 

The three symmetrically positioned electrophilic centers of trichlorotriazine enable the selective introduction of points of diversity through successive substitution of the chlorine atoms. This feature of trichlorotriazine is well known and widely utilized, e. g., in the chemistry of dyestuffs. The principle has been applied for the preparation of a 12000-membered library [126] for use in both solid-phase and solution assays, -with a selectively cleavable linker stable to the TFA treatment necessary for the deprotection of functional groups present. Methionine was used as a suitable linker between the library and the resin. This type of linkage to the support has been used previously for release of the compounds for mass spectro-metric analysis [127]. Both the first and second chlorine atoms of the triazine scaffold can be substituted at room temperature, but the kinetics of the two reac-... 

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