Tadashi Nakai

The reaction of tryptophan with cystine during acid hydrolysis of proteins: Formation of tryptathionine as a transient intermediate in a model system

Under the conditions commonly used to hydrolyze proteins with 6 M HCl, tryptophan reacted with cystine to give a transient intermediate, which was isolated and identified as 2-(2-amino-2-carboxyethylthio)tryptophan (tryptathionine) by NMR studies, etc. Studies on the formation and degradation of the above compound showed that beta-3-oxoindolylalanine and cysteine, which were previously reported to be the main degradation products of tryptophan and cystine, respectively, are formed by the hydrolysis of this intermediate during the course of the reaction.

Thin-layer chromatographic detection of glycolaldehyde using a fluorescence reaction with o-aminodiphenyl

Abstract It was found that glycolaldehyde reacted with o-aminodiphenyl in the presence of sulphuric acid on silica gel thin-layer chromatograms to form a compound which, on UV irradiation, gave an intense bluish white fluorescence. This reaction was used to detect glycolaldehyde in complex mixtures of sugars. The reversible interconversion of the monomer and dimer of glycolaldehyde is discussed.

Acid Saccharification of Cellulose Acetate

The effect of the introduction of acetyl groups into cellulose on its acid saccharification was investigated. Cellulose, DS 2.87- and DS 2.36-cellulose acetates and regenerated celluloses from the acetates were saccharified at 100 and 135°C by using 0.4, 0.8 or 1.6% solutions of sulfuric acid as hydrolyzing agents. The cellulose acetates were far more readily saccharified than cellulose. The regenerated celluloses could not so readily be saccharified as the acetates. It is suggested that the ease of saccharification of cellulose acetates might be due principally to some alteration in the crystallite (micell) structure caused by the introduction of acetyl groups into cellulose molecules.