Interaction of the Bacterial Ribonuclease Binase with the Polypeptide Inhibitor Barstar Based on Kinetic Data on Poly(U) Hydrolysis

L. O. Yagodina

Kazan Institute of Biochemistry and Biophysics, Kazan Research Center of the Russian Academy of Sciences, ul. Lobachevskogo 2/31, Kazan, 420503 Russia; fax: (8432) 387-577; E-mail: yagodina@sci.kcn.ru

Received May 25, 2000; Revision received October 7, 2000

---

The reaction of poly(U) hydrolysis catalyzed by binase while the latter is inhibited by barstar has been investigated. The inhibition constant for barstar and the apparent Michaelis constants for the inhibition by barstar in the presence of ethanol and NaCl have been determined. Both ethanol and NaCl enhance the inhibition by barstar. This suggests that the binding of barstar with binase is probably due to the interaction of hydrophobic sites rather than by electrostatic interaction between amino acid residues.

---

KEY WORDS: binase, barstar, poly(U) hydrolysis, enzymatic catalysis, kinetics, hydrophobic interaction

---