38
Biochemistry 1993, 32, 38-47
Art ides
Reaction of the Isosteric Methylenephosphonate Analog of a-D-Glucose 1-Phosphate with Phosphoglucomutase. Induced-Fit Specificity Revisited7 William J. Ray, Jr.,’ Carol Beth Post,* and Joseph M. Puvathingal Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907 Received April 21, 1992; Revised Manuscript Received June 15, 1992
ABSTRACT: The phospho form of phosphoglucomutase reacts with the isosteric methylenephosphonate analog of a-D-glucose 1-phosphate to produce the corresponding analog of a-D-glucose 1,6-bisphosphate plus the dephosphoenzyme. In a coupled reaction, kCatfKm= 1.7 X lo3 M-’ s-l, which is about 2 X times that for the corresponding reaction with a-D-glucose 1-phosphate. The decrease in k,a,fKm is divided more or less evenly between less efficient PO3- transfer and decreased binding, although smaller phosphates and phosphonates bind approximately equally. There is a much smaller difference in the binding of glucose 1-methylenephosphonate 6-phosphate and glucose 1,6-bisphosphate to the dephosphoenzyme: the binding ratio is
