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solation and characterization of monodeamidated derivatives of bovine pancreatic Ribonuclease A

Venkatesh, Yeldur P and Vithayathil, Paul J (1984) solation and characterization of monodeamidated derivatives of bovine pancreatic Ribonuclease A. In: International Journal of Peptide and Protein Research, 23 (5). pp. 494-505.

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Official URL: http://www3.interscience.wiley.com/journal/1215294...

Abstract

The isolation and characterization of the initial intermediates formed during the irreversible acid denaturation of enzyme Ribonuclease A are described. The products obtained when RNase A is maintained in 0.5 M HCl at 30° for periods up to 20 h have been analyzed by ion-exchange chromatography on Amberlite XE-64. Four distinct components were found to elute earlier to RNase A; these have been designated RNase Aa2, Aa1c, Aa1b, and Aa1a in order of their elution. With the exception of RNase Aa2, the other components are nearly as active as RNase A. Polyacrylamide gel electrophoresis at near-neutral pH indicated that RNase Aa1a, Aa1b, and Aa1c are monodeamidated derivatives of RNase A; RNase Aa2 contains, in addition, a small amount of a dideamidated component. RNase Aa2, which has 75% enzymic activity as compared to RNase A, consists of dideamidated and higher deamidated derivatives of RNase A. Except for differences in the proteolytic susceptibilities at an elevated temperature or acidic pH, the monodeamidated derivatives were found to have very nearly the same enzymic activity and the compact folded structure as the native enzyme. Fingerprint analyses of the tryptic peptides of monodeamidated derivatives have shown that the deamidations are restricted to an amide cluster in the region 67–74 of the polypeptide chain. The initial acid-catalyzed deamidation occurs in and around the 65–72 disulfide loop giving rise to at least three distinct monodeamidated derivatives of RNase A without an appreciable change in the catalytic activity and conformation of the ribonuclease molecule. Significance of this specific deamidation occurring in highly acidic conditions, and the biological implications of the physiological deamidation reactions of proteins are discussed.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Wiley Interscience.
Keywords: amide cluster;Amberlite XE-64;Asn-Gly sequence;deamidation; 65–72 disulfide loop;monodeamidated derivatives;RNase A.
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 09 Feb 2010 07:07
Last Modified: 09 Feb 2010 07:07
URI: http://eprints.iisc.ernet.in/id/eprint/22915

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