The structure of E. coli beta-galactosidase.
E. coli beta-galactosidase is a tetramer of four identical 1023-amino acid chains. Each chain consists of five domains, the third of which is an eight-stranded alpha/beta barrel that comprises much of the active site. This site does, however, include elements from other domains and other subunits. The N-terminal region of the polypeptide chains help form one of the subunit interfaces. Taken together these features provide a structural basis for the well-known property of alpha-complementation. Catalytic activity proceeds via the formation of a covalent galactosyl intermediate with Glu537, and includes 'shallow' and 'deep' modes of substrate binding.
Matthews
Brian W
BW
Institute of Molecular Biology, Howard Hughes Medical Institute and Department of Physics, 1229 University of Oregon, Eugene, OR 97403-1229, USA. brian@uoxray.uoregon.edu
D001665:Binding Sites; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D006860:Hydrogen Bonding; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D001616:beta-Galactosidase / Q000737:chemistry*
D001616:beta-Galactosidase; D008274:Magnesium