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Spectroscopy
Volume 22 (2008), Issue 4, Pages 279-286
http://dx.doi.org/10.3233/SPE-2008-0350

Structural lesion to ribonuclease A caused by reductive stress: Assessment by Raman spectroscopy

Armida Torreggiani

Consiglio Nazionale delle Ricerche, Istituto ISOF, via P. Gobetti 101, 40129 Bologna, Italy

Copyright © 2008 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The damages induced by reductive radical stress on bovine pancreatic ribonuclease A (RNAse A) were investigated by Raman spectroscopy. Gamma-irradiation was used to simulate the endogenous formation of reductive species, in particular H atom that is a simple one-electron equivalent reducing agent. Specific damages occur at sensitive amino acid sites, selectively, rather than indiscriminately, leading to the structure modification of the protein. Sulfur-containing residues (Met and Cys) and aromatic residues are appreciably attacked. In particular, extensive changes in the disulfide bridge conformations are induced as well as conformational changes of the protein secondary structure; a gradual conversion of α-helical to pleated-sheet geometry was evidenced, indicating a higher ability of reducing radicals in denaturing the protein structure compared with that of oxidizing radical species.