β-1,3-Endoglucanase from Soybean Releases Elicitor-Active Carbohydrates from Fungus Cell Walls

Abstract

Two enzymes from soybean (Glycine max L. Merr. cv Harosoy 63) cotyledons released elicitor-active carbohydrates from cell walls of the phytopathogenic fungus Phytophthora megasperma f.sp. glycinea. They were identified as isoenzymes of β-1,3-endoglucanase (EC 3.2.1.39) with isoelectric points of pH 8.7 and 10.5. The pI 10.5 enzyme was extracted in the greatest amount and was isolated as a homogeneous protein of about 33,000 daltons as determined by gel filtration and sodium dodecyl sulfategel electrophoresis. The purified enzymes hydrolyzed several β-1,3-glucans in a strictly random manner, but degraded neither β-1,6- nor β-1,4-glucans.