title: Properties of ATP and UTP analogues with P-S-C-5' bonds.
abstract: Analogues of ATP and UTP bearing C-5'-S-P ester bonds were found not to be substrates but weak competitive inhibitors of Escherichia coli RNA polymerase. The K-i values of the analogues obtained in the transcription of poly[d(A-T)] or poly(dT) under various conditions are in the order of millimolar. Evidence was derived from proton magnetic resonance spectra that nucleotides with C-5'-S-P bonds do not exist in gauche-gauche conformation normally adopted by natural occurring nucleotides. This leads us to assume that the gauche-gauche conformation is an essental prerequisite for substrates of RNA polymerase. Ado-5'-S-PPP substituted for ATP as substrate of hexokinase from yeast rather effectively thus indicating that a distinct stereochemical orientation of the alpha-phosphate ester bond is not a stringent requirement for substrates of this enzyme.
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds; D014158:Transcription, Genetic; D014500:Uracil Nucleotides
chemical_list: D013438:Sulfhydryl Compounds; D014500:Uracil Nucleotides; D000255:Adenosine Triphosphate; D012321:DNA-Directed RNA Polymerases