Pumpkin (Cucurblta sp.) seed globulin V. Proteolytic activities involved in globulin degradation in ungerminated seeds

概要

論文の詳細を見る
Two proteolytic activities I and II involved in the globulin degradation were detected in pumpkin seeds. Activity I, hydrolyzing α and β subunits of the globulin to form F_<αβ>, was found in both dry seeds and cycloheximide-treated cotyledons, and de-creased during germination. Activity II, hydrolyzing F_<αβ> to produce small peptides and amino acids, was not observed in dry seeds but found in cycloheximide-treated cotyledons, increased up to 4 days, and gradually decreased during germination. Activity I gave limited hydrolytic products from the globulin and the γ' chain, but not from F_<αβ>, the δ chain and some animal proteins. It was inhibited by EDTA. On the other hand, activity II hydrolyzed F_<αβ> and the δ chain faster than the globulin, the γ' chain and some animal proteins. It was inhibited by EDTA and p-chloromercuribenzoate, and activated by β-mercaptoethanol, dithiothreitol and CoCl_2. Optimum pH's were at about 6.8 and at 6.0 to 6.8 for activities I and II, respectively. The degradation process of the globulin can be divided into two steps: the first step is the conversion of globulin to F_<αβ> and the second step, F_<αβ> to small peptides and amino acids.
日本植物生理学会の論文