2'-Deoxy-2'-fluorouridine-5'-phosphate: an alternative substrate for thymidylate synthetase from Escherichia coli K12.
The substrate specificity of 2'-deoxy-2'-substituted uridines and their 5'-phosphates towards thymidylate synthetase from Escherichia coli K12 was investigated. Besides the natural substrate 2'-deoxyuridine-5'-phosphate (dUMP), only 2'-deoxy-2'-fluorouridine-5'-phosphate (dUflMP) was a substrate. The KM of dUflMP is 11 times higher than that of dUMP, while the Vmax values are virtually the same. It is concluded that the size of the 2'-substituent and not its polarity (and the concomitant conformational change) determines substrate specificity of thymidylate synthetase.
D003856:Deoxyuracil Nucleotides; D004926:Escherichia coli / Q000201:enzymology*; D005468:Fluorodeoxyuridylate; D007700:Kinetics; D008780:Methyltransferases / Q000378:metabolism*; D008968:Molecular Conformation; D013379:Substrate Specificity; D013940:Thymidylate Synthase / Q000378:metabolism*
D003856:Deoxyuracil Nucleotides; D005468:Fluorodeoxyuridylate; D008780:Methyltransferases; D013940:Thymidylate Synthase