STRUCTURE INVESTIGATION OF CELLOBIOHYDROLASE-I FROM TRICHODERMA-PSEUDOKONINGII S38 WITH A SCANNING TUNNELING MICROSCOPE

Cellobiohydrolase I (CBH I) was isolated from a cellulolytic fungal st rain Trichoderma pseudokoningii S38, and its ultrastructure was invest igated with a scanning tunneling microscope (STM). The STM images show ed that the shape of intact CBH I was tadpole-like, consisting of a bi g head and a long tail. It could be deduced that the head domain was t he core protein for the catalytic function, and the long tail was the cellulose binding domain for substrate binding. Thus, for this enzyme molecule, functional differentiation is reflected in the structure pec uliarities. This is the first direct observation of the three-dimensio nal structure of intact CBH I from real space at nanometer scale. The functional mechanism is also discussed.