Purification and characterization of two endo-beta-1,4-D-glucanases from Sclerotinia sclerotiorum

The endo-beta-1,4-D-glucanase (EC 3.2.1.4) enzymes produced in vitro by Sclerotinia sclerotiorum consisted of numerous isoforms with pI ranging from 3.5 to 6.2. The two dominant isoforms, labelled EG1 and EG2, were purified. The pI of EG1 and EG2 were 6.2 and 3.7, respectively. Their molecular weights were, respectively, 48,000 and 34,000. EG1 and EG2 were both active towards carboxymethyl cellulose. However, EG1 was also active towards 4-methylumbelliferyl cellobioside. The amino acid compositions of EG1 and EG2 were different. The N-terminal amino acid sequences of the two enzymes showed little homology. However, the N-terminal sequence of EG1 showed considerable homology to the published N-terminal sequence of an endoglucanase (EG1) from Schizohyllum commune.