麹酵素による蛋白質の分解(第1報)

Abstract

Oryzenin, the principal protein of milled rice, was fractionated into 3 fractions by Sepharose 4B gel filtration. The hydrolysis of oryzenin by the acid protease prepared from Taka-diastase was examined at several pH; 3.0, 4.0 and 6.0. (1) Optimum pH of the acid protease for the hydrolysis of oryzenin was found to be near 3.0. (2) Ratios of lower molecular peptides (phosphotungstic acid-soluble fraction) to higher molecular peptides (trichloroacetic acid-soluble fraction) liberated from oryzenin by the enzyme were determined occasionally during the long time reactions and it was found that the ratios were higher when reacted at pH 4.0 or 6.0 than at pH 3.0. (3) Elution patterns of the protein fractions of the reactants from Sepharose 4B column were obtained at times during the reactions. The gel filtration patterns were somewhat different depending on the reaction pH; Fraction I (eluted at void volume and considered to be the largest molecular fraction) disappeared rapidly and completely when reacted at pH 4.0 and the disappearance of Fraction II (eluted succesive to Fraction I) was comparatively rapid at pH 3.0. (4) Lower molecular fractions of the reactants were occasionally fractionated by Sephadex G-15 gel filtration during the reactions. It was also found that the gel filtration patterns were somewhat different depending on the reaction pH; When the protein was reacted at pH 3.0, there appeared several peaks in the gel filtration pattern between the high molecular fraction (void volume) and the small molecular fraction (eluting out volume)mainly consisted of free amino acids presumably, while these peaks were not appeared at all when the protein was reacted at pH 4.0 or 6.0. (3) Amino acid liberation patterns were again different depending on the reaction pH; Amounts of the liberated amino acids were larger when reacted at pH 4.0 or 6.0 than at pH 3.0.