Activation of galactanase from Penicillium citrinum by its binding with mercury.

Abstract

When a galactanase from Penicillium citrinum was incubated with HgCl2 in the presence of KC1, mercury bound to the enzyme at one g atom per mol. The modified enzyme had increased activity on 0-nitrophenyl-β-d-galactopyranoside (ONPG) compared to the native enzyme and there was no more increase in the activity with further treatment with HgCl2. The activity of the modified enzyme on soybean arabinogalactan and o-nitrophenol-substituted galactooligosaccharides, on the other hand, decreased to 70 ~ 80% of that of the native one. The modified enzyme had the same UV spectrum, molecular weight, isoelectric point, and CD spectrum as those of the native enzyme.Mercury bound to the modified enzyme could be removed by dialysis against a reduced glutathione solution and the activity on ONPG of the enzyme reverted to that of the native one, indicating the reversibility of the modification.