CIRCULAR-DICHROISM STUDIES ON CONFORMATION OF CELLOBIOHYDROLASE AND ENDOGLUCANASE FROM TRICHODERMA-PSEUDOKININGII S-38 - EFFECTS OF PH AND LIGAND-BINDING

Effects of pH and ligand binding upon the conformation of cellobiohydr olase I (CBHI) and endoglucanase I (EGI) from Trichoderma pseudokining ii S-38 have been studied by circular dichroism measurements. In the h igh-pH range (6-9), increasing pH resulted in a similar conformational change occurring in free CBHI and EGI, while such treatment gave diff erent changes of the two enzyme conformations in the presence of cello biose. On the other hand, in the low-pH region, with both CBHI an EGI in the active form, decreasing pH resulted in a large conformational c hange of free EGI compared to that of free CBHI, whereas ligand bindin g resulted in a similar change of both CBHI and EGI, independent of pH change.