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Spectroscopic studies on the mode of binding of ATP, UTP and α‐amanitin with yeast RNA polymerase II
Author(s) -
Bhargava Purnima,
Chatterji Dipankar
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)81025-1
Subject(s) - rna polymerase , enzyme , nucleoside triphosphate , biochemistry , nucleotide , polymerase , substrate (aquarium) , chemistry , titration , yeast , microbiology and biotechnology , tryptophan , biology , rna , stereochemistry , amino acid , gene , inorganic chemistry , ecology
The binding affinity between the substrates ATP and UTP with the purified yeast RNA polymerase II have been studied here in the presence and absence of Mn 2+ . In the absence of template DNA, both ATP and UTP showed tight binding with the enzyme without preference for any specific nucleotide, unlike Escherichia coli RNA polymerase. Fluorescence titration of the tryptophan emission of the enzyme by nucleoside triphosphate substrates gave an estimated K d value around 65 μM in the absence of Mn 2+ whereas in the presence of Mn 2+ , the K d was 20 μM. The effect of substrates on the longitudinal relaxation of the HDO proton in enzyme‐substrate complex also yielded a similar K d value.