Annual Progress Report, December 1958-December 1961.
IOWA STATE UNIV IOWA CITY
Pagination or Media Count:
The ribonuclease RNase molecule which takes part in the formation of enzyme-substrate complexes, was investigated to determine factors which affect the binding of various competitive inhibitors of RNase activity. The binding of inhibitory nucleotides, such as 2-cytidylic acid, by RNase was measured not only by enzyme inhibition, but also by spectral changes and dialysis equilibrium. As measured spectrophotometrically, complex formation between nucleotideAND RNase is manifested by changes in the spectral contributions from both pyrimidine and tyrosyl groups. The affinities of RNase for 2-cytidylic acid as measured by all 3 methods were in excellent agreement. As measured by dialysis equilibrium and spectral changes, only one molecule of nucleotide is bound per molecule of enzyme. Since 2-cytidylic acid is a competitive inhibitor of both catalytic actions transferase and hydralase of the enzyme, it may be inferred that the same catalytic site is responsible for both reactions. Author