Characterization of germinated barley endoproteolytic enzymes by two-dimensional gel electrophoresis
1995; Elsevier BV; Volume: 21; Issue: 2 Linguagem: Inglês
10.1016/0733-5210(95)90030-6
ISSN1095-9963
AutoresNingyan Zhang, Berne L. Jones,
Tópico(s)Proteins in Food Systems
ResumoGerminating barley proteolytic enzymes hydrolyze insoluble seed storage proteins into soluble proteins, peptides and amino acids. This process is of vital importance to both seed germination and the commercial malting process. This study reports the development of a two-dimensional IEF × PAGE separation method utilizing protein substrates incorporated into the PAGE gel to analyze and partially characterize the endoproteinases of germinating barley grain. The method separated 42 different activities, which fell into five groups on the basis of their pI values, PAGE mobilities and biochemical characteristics. Multiple representatives of each of the four proteinase classes were present, but about 64% of the enzymes were cysteine proteinases. The majority of the endoproteinases had pH optima considerably below neutrality, but those of the serine proteinases were generally eight or higher. Most of the endoproteinases hydrolyzed gelatin faster than edestin, but the four aspartic class proteinases and one of an undetermined class only hydrolyzed edestin. These results show that the protein-hydrolyzing system of green malt (4-day-old germinated barley) is very complex.
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