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Open Journal of Biology and Biochemistry

ISSN: 2227-7021
Volume 2, 2017


Open Journal of Biology and Biochemistry, 2012, 1-3 [Research Article]

Comparative characterization of the ribonuclease A homologue Rana catesbeiana ribonuclease 3

Nadine Heimer, Ulrich Arnold
Martin-Luther University Halle-Wittenberg, Institute of Biochemistry and Biotechnology, Kurt-Mothes Str. 3, 06120 Halle, Germany

Corresponding Author & Address:

Ulrich Arnold
Martin-Luther University Halle-Wittenberg, Institute of Biochemistry and Biotechnology, Kurt-Mothes Str. 3, 06120 Halle, Germany; Phone: +49 345 5524864; Fax: +49 345 5527303; Email: ulrich.arnold@biochemtech.uni-halle.de; URL: www.biochemtech.uni-halle.de/biotech

Article History:
Published: 22nd September, 2012   Accepted: 22nd September, 2012
Received: 12th July, 2012      

© Arnold et al.; licensee Ross Science Publishers

ROSS Open Access articles will be distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided that the original work will always be cited properly.

Keywords: ribonuclease, homologous proteins, stability, unfolding

Abstract:

A promising approach to unriddle the interrelation between amino acid sequence, tertiary structure, and protein stability is the comparison of homologous proteins. An excellent model system is provided by the ribonuclease A superfamily whose members can be found in all branches of the vertebrata subphylum. Though ribonuclease A has served as a model protein for decades, rather little is known about the folding of its homologues. It was only recently that the folding pathway of onconase, an unusually stable ribonuclease A homologue from the Northern leopard frog, was dissected [Schulenburg et al., Biochemistry. 2009; 48(35): 8449-8457]. As also other ribonuclease A homologues from amphibians were found to be more stable than ribonuclease A itself we analyzed the thermodynamic stability and thermal unfolding of ribonuclease 3 from bullfrog, which shares 55% sequence identity with onconase. Ribonuclease 3 was found to be more stable than ribonuclease A by ~ 15°C in both equilibrium and kinetics experiments. In contrast, the extent of the thermodynamic stabilization of onconase is much greater than its kinetic stabilization pointing to differences in the folding behavior of the two amphibian ribonucleases. Moreover, though being thermally less stable than onconase, ribonuclease 3 unfolds at significantly higher concentrations of guanidine hydrochloride than onconase.



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