Inosine 5'-monophosphate dehydrogenase of Escherichia coli K12: the nature of the inhibition by guanosine 5'-monophosphate.
When IMP is the variable substrate, IMP dehydrogenase (EC 1.2.1.14) gives non-linear Lineweaver-Burk plots in the presence of GMP. At 0.1mm-GMP the Hill coefficient n=1.15 and at 0.2mm-GMP n=1.34. In the absence of GMP n=1.0. The fact that n exceeds 1.0 in the presence of GMP indicates that the enzyme possesses regulatory (allosteric) properties. The inhibition by GMP is competitive with respect to IMP and non-competitive with respect to NAD(+).
D004926:Escherichia coli / Q000201:enzymology*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D007292:Inosine Nucleotides; D007658:Ketone Oxidoreductases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D009243:NAD
D006150:Guanine Nucleotides; D007292:Inosine Nucleotides; D009243:NAD; D007658:Ketone Oxidoreductases