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EVIDENCE FOR THE PRESENCE OF MALTASE AND α‐GLUCOSIDASE ISOENZYMES IN BARLEY
Author(s) -
Stark J. R.,
Yin X. S.
Publication year - 1987
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1987.tb04485.x
Subject(s) - maltase , isomaltose , glucosidases , maltose , chemistry , beta glucosidase , alpha glucosidase , hydrolysis , thermostability , biochemistry , sucrase , enzyme , glucoside , sucrose , chromatography , glycoside hydrolase , enzyme assay , medicine , alternative medicine , pathology
An examination of the development of α‐glucosidase and maltase activities (as measured by the hydrolysis of p‐nitrophenyl α‐D‐glucoside and maltose respectively) indicated that two genotypes of Glacier barley had the same general pattern of enzyme development. However, the development of α‐glucosidase activity followed a different course from that of maltase activity suggesting that separate enzyme proteins are involved in hydrolysing these substrates. Further evidence that separate enzyme proteins were responsible for hydrolysis of maltose and p‐nitrophenyl α‐glucoside was obtained by column chromatography of extracts of germinated barley which indicated the presence of two maltases and two α‐glucosidases. The maltases and the α‐glucosidases differed in molecular weight, pH of optimum activity and in thermostability. When isomaltose was used as a substrate the optimum pH and behaviour on gel chromatography were coincident with that of maltase activity but different from the α‐glucosidases.