Quantitative Bestimmung von freiem neben peptidgebundenem Methionin in Form des β-Methylmercapto-propionaldehyd-2.4-dinitrophenylhydrazons

Abstract

[beta]-Methylmercaptopropionaldehyde is obtained from free methionine by treatment with ninhydrin. Separation of the aldehyde as its dinitrophenyl-hydrazone is carried out by column chromatography, and the compound estimated colorimetrically. Sugars, salts and other substances do not interfere with the procedure which is suitable for routine determinations. Free and peptide-linked methionine can be determined by estimation before and after hydrolysis. Methionine labeled with S35 can be determined readily. A paper chromatographic method using methanol/ heptane as solvent system is also described for the separation of the dinitrophenylhydrazones of aldehydes. The method is applied to the aldehydes which are volatile in steam and are obtained from phenylalanine, valine, leucine and isoleucine by treatment with ninhydrin.