title: On the functional role of the Tyr-639 residue of bacteriophage T7 RNA polymerase.
abstract: Substitution of Asp for a Tyr residue normally present at position 639 of the bacteriophage T7 RNA polymerase leads to a drastic drop in the enzymatic activity. This mutation does not affect the enzyme-promoter interaction but decreases the ability of the RNA polymerase to discriminate between GTP and ATP molecules, resulting in a decrease in the rate of the incorporation of the nucleotide into the RNA chain.
authors.affiliation: V.A. Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow.
authors.forename: V O
authors.initials: VO
authors.lastname: Rechinsky
authors.forename: D A
authors.initials: DA
authors.lastname: Kostyuk
authors.forename: V L
authors.initials: VL
authors.lastname: Tunitskaya
authors.forename: S N
authors.initials: SN
authors.lastname: Kochetkov
mesh_terms: D000595:Amino Acid Sequence; D001667:Binding, Competitive; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D013604:T-Phages / Q000201:enzymology; D014443:Tyrosine / Q000502:physiology*; D014764:Viral Proteins
chemical_list: D014764:Viral Proteins; D014443:Tyrosine; C062210:bacteriophage T7 RNA polymerase; D012321:DNA-Directed RNA Polymerases