Acid Glycosidase Isoenzymes and Activities in Developing Hulls and Seeds of Pisum sativum L.

Abstract

Summary The changes in β-glucosidase (EC 3.2.1.21), β-galactosidase (EC 3.2.1.23), α-mannosidase (EC 3.2.1.24) and α-glucosidase (EC 3.2.1.20) activities that occur during development of the pea seed have been measured. The highest tissue specific activity of β-glucosidase is found in the seedcoats, whereas the highest specific activities of the other enzymes occur in the cotyledons. Glycosidase isoenzymes were separated by ammonium sulphate fractionation followed by anion exchange chromatography and gel filtration. The α-mannosidase and β-galactosidase activities of the cotyledons are attributed mainly to single forms of each specific enzyme of MW 70,000 and 46,000 daltons respectively. By comparison, a wider spectrum of isoenzymes was observed in the hull and seedcoats. For seedcoats, two forms of β-glucosidase, three forms of β-galactosidase and four forms of α-mannosidase were distinguished. The main form of β-glucosidase from the seedcoats, isoenzyme 2, had a MW estimated to be 65,000 daltons.