IMAGING GLUCOAMYLASE BY SCANNING-TUNNELING-MICROSCOPY

Images of the enzymes glucoamylase 1 and glucoamylase 2 and G1C (a pro teolytically derived C-terminal fragment of glucoamylase 1) have been obtained by scanning tunnelling microscopy (STM). The images of glucoa mylase 2 and G1C show that these proteins are nearly spherical globula r proteins. In contrast, images of glucoamylase 1 show that it is a du mb-bell shaped globular protein. Problems encountered in (i) imaging t hese proteins and (ii) validating and interpreting the images obtained by STM are discussed.