Accession Number : AD0451069

Title :   RELAXATION SPECTRA OF RIBONUCLEASE. I. THE INTERACTION OF RIBONUCLEASE WITH CYTIDINE 3'-PHOSPHATE,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Cathou,Renata E. ; Hammes,Gordon G.

Report Date : 18 MAR 1964

Pagination or Media Count : 6

Abstract : Kinetic studies of the interaction of bovine pancreatic ribonuclease with cytidine 3'-phosphate have been made at high enzyme concentrations using the temperature jump method. Two different relaxation processes with characteristic relaxation times ranging from about 1 msec. to less than 20 microseconds have been observed. One process is concentration dependent and is observed at all pH's in the range studied (pH 5.0-7.5). This effect is due to the formation of the enzyme-substrate complex; the rate constants for both complex association and dissociation were determined and interpreted in terms of elementary mechanistic steps involving an enzyme group with a pK of 6.7 in the free enzyme. The other relaxation process is observed only when the enzyme is essentially all in the form of the enzyme-cytidine 3'-phosphate complex. The relaxation time is concentration independent, suggesting an intramolecular process. Moreover, the variation of the relaxation time with pH is much greater than that expected for the participation of a single ionizing group; i.e., a cooperative process is occurring. (Author)

Descriptors :   (*RIBONUCLEASE, SPECTROSCOPY), (*RELAXATION TIME, RIBONUCLEASE), KINETIC THEORY, PHOSPHATES, PHYSICAL CHEMISTRY, PH FACTOR, MOLECULAR PROPERTIES, BIOCHEMISTRY, RIBONUCLEIC ACIDS, ENZYMES

Distribution Statement : APPROVED FOR PUBLIC RELEASE