2. ES complexes have been directly visualized by electron microscopy, as in the micrograph of DNA polymerase I bound to its DNA template(Figure 8-9). X-ray crystallography has provided high-resolution images of sub- Figure 8-9 Electron micrograph of DNA polymerase I mole- cules(white spheres bound to a threadlike synthetic DNA template. [ Courtesy of Dr Jack Griffith strates and substrate analogs bound to the active sites of many enzymes
Nicholas R. Cozzarelli Professor of Biochemistry Molecular Biology
3. The spectroscopic characteristics of many enzymes and substrates change upon formation of an Es complex These changes are particularly striking if the enzyme contains a colored prosthetic group. Tryptophan synthetase, a bacterial enzyme that contains a pyridoxal phosphate prosthetic group, affords a nice illustra- tion c subunit Indole-3-glycerol phosphate indole glyceraldehyde 3-phosphate Indole +serine Ba subunit, tryptophan+H2O