FROM RIBONUCLEASE-A TOWARD BOVINE SEMINAL RIBONUCLEASE - A STEP-BY-STEP THERMODYNAMIC ANALYSIS

Citation
F. Catanzano et al., FROM RIBONUCLEASE-A TOWARD BOVINE SEMINAL RIBONUCLEASE - A STEP-BY-STEP THERMODYNAMIC ANALYSIS, Biochemistry, 36(47), 1997, pp. 14403-14408
Citations number
35
Language
INGLESE
art.tipo
Article
Journal title
Biochemistry → ACNP
ISSN journal
0006-2960
Volume
36
Issue
47
Year of publication
1997
Pages
14403 - 14408
Database
ISI
SICI code
0006-2960(1997)36:47<14403:FRTBSR>2.0.ZU;2-L
Abstract
A proline, a leucine, and two cysteine residues, introduced at positio ns 19, 28, 31, and 32 of bovine pancreatic RNase A, i.e. the positions occupied by these residues in the subunit of bovine seminal RNase, th e only dimeric RNase of the pancreatic-type superfamily, transform mon omeric RNase A into a dimeric RNase, endowed with the same ability of BS-RNase of swapping its N-terminal segments. The thermodynamic conseq uences of the progressive introduction of these four residues into RNa se A polypeptide chain have been studied by comparing the temperature- and urea-induced denaturation of three mutants of RNase A with that of a stable monomeric derivative of BS-RNase. The denaturation processes proved reversible for all proteins, and well represented by the two-s tate N double left right arrow D transition model. The progressive int roduction of the four residues into RNase A led to a gradual shift of the protein stability toward that characteristic of monomeric BS-RNase , which, in turn, is markedly less stable than RNase A with respect to both temperature-and urea-induced denaturation. On the other hand, th e thermal stability of a dimeric active mutant of RNase A is found to approach that of wild-type seminal RNase.