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Computer modelling studies on the mechanism of action of ribonuclease T1

Balaji, PV and Saenger, W and Rao, VSR (1991) Computer modelling studies on the mechanism of action of ribonuclease T1. In: Journal of Biomolecular Structure & Dynamics, 9 (2). pp. 215-231.

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Official URL: http://www.ncbi.nlm.nih.gov/pubmed/1741959


The mechanism of action of ribonuclease (RNase) T1 is still a matter of considerable debate as the results of x-ray, 2-D nmr and site-directed mutagenesis studies disagree regarding the role of the catalytically important residues. Hence computer modelling studies were carried out by energy minimisation of the complexes of RNase T1 and some of its mutants (His40Ala, His40Lys, and Glu58Ala) with the substrate guanyl cytosine (GpC), and of native RNase T1 with the reaction intermediate guanosine 2',3'-cyclic phosphate (G greater than p). The puckering of the guanosine ribose moiety in the minimum energy conformer of the RNase T1-GpC (substrate) complex was found to be O4'-endo and not C3'-endo as in the RNase T1-3'-guanylic acid (inhibitor/product) complex. A possible scheme for the mechanism of action of RNase T1 has been proposed on the basis of the arrangement of the catalytically important amino acid residues His40, Glu58, Arg77, and His92 around the guanosine ribose and the phosphate moiety in the RNase T1-GpC and RNase T1-G greater than p complexes. In this scheme, Glu58 serves as the general base group and His92 as the general acid group in the transphosphorylation step. His40 may be essential for stabilising the negatively charged phosphate moiety in the enzyme-transition state complex.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Adenine Press.
Keywords: Histidine-Residues;Nucleic-Acids;N-Tau-Carboxymethylhistidine-12 Ribonuclease;Conformational Stability;Catalytic Mechanism;Rna Hydrolysis;Force-Field; Amino-Acid;Nucleotides;Imidazole.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Depositing User: Ms Mary Ranjeetha
Date Deposited: 10 Nov 2010 05:21
Last Modified: 10 Nov 2010 05:21
URI: http://eprints.iisc.ac.in/id/eprint/33713

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