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Irreversible Thermal Denaturation Of Bovine Pancreatic Ribonuclease-A

Ramnath, S and Vithayathil, Paul J (1981) Irreversible Thermal Denaturation Of Bovine Pancreatic Ribonuclease-A. In: International Journal Of Peptide And Protein Research, 17 (1). pp. 107-117.

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Official URL: http://www3.interscience.wiley.com/journal/1215926...


The isolation and characterization of the products formed during the irreversible thermal denaturation of enzyme RNAase-A are described. RNAase-A, when maintained in aqueous solution at pH 7.0 and 70° for 2 h, gives soluble products which have been fractionated by gel filtration on Sephadex G-75 into four components. These components are designated RNAase-At1, RNAase-At2, RNAase-At3 and RNAase-At4 according to the order of their elution from Sephadex G-75. RNAase-At4 shows the same specific activity towards yeast RNA as native RNAase-A and is virtually indistinguishable from it by the physical methods employed. However, chromatography on CM-cellulose separates it into three components that show the same u.v. spectra and specific activity towards yeast RNA as native RNAase-A. RNAase-At1, RNAase-At2and RNAase-At3 are all structurally altered derivatives of RNAase-A and they exhibit low specific activity (5–10%) towards yeast RNA. In the presence of added S-protein, all these derivatives show greatly enhanced enzymic activity. RNAase-At1 and RNAase-At2 are polymers, covalently crosslinked by intermolecular disulfide bridges; whereas RNAase-At3 is a monomer. Physical studies such as 1H-n.m.r., sedimentation analysis, u.v. absorption spectra and CD spectra reveal that RNAase-At3 is a unfolded derivative of RNAase-A. However, it is seen to possess sufficient residual structure which gives rise to a low but easily detectable enzymic activity.

Item Type: Journal Article
Publication: International Journal Of Peptide And Protein Research
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 27 Aug 2009 04:46
Last Modified: 27 Aug 2009 04:46
URI: http://eprints.iisc.ac.in/id/eprint/22543

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