1m07

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spinqualitylabelsall models 1m07, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

RESIDUES INVOLVED IN THE CATALYSIS AND BASE SPECIFICITY OF CYTOTOXIC RIBONUCLEASE FROM BULLFROG (RANA CATESBEIANA)

Overview

The Rana catesbeiana (bullfrog) ribonucleases, which belong to the RNase A, superfamily, exert cytotoxicity toward tumor cells. RC-RNase, the most, active among frog ribonucleases, has a unique base preference for, pyrimidine-guanine rather than pyrimidine-adenine in RNase A. Residues of, RC-RNase involved in base specificity and catalytic activity were, determined by site-directed mutagenesis, k(cat)/K(m) analysis toward, dinucleotides, and cleavage site analysis of RNA substrate. The results, show that Pyr-1 (N-terminal pyroglutamate), Lys-9, and Asn-38 along with, His-10, Lys-35, and His-103 are involved in catalytic activity, whereas, Pyr-1, Thr-39, Thr-70, Lys-95, and Glu-97 are involved in base, specificity. The cytotoxicity of RC-RNase is correlated, but not, proportional to, its catalytic activity. The crystal structure of the, RC-RNase.d(ACGA) complex was determined at 1.80 A resolution. Residues, Lys-9, His-10, Lys-35, and His-103 interacted directly with catalytic, phosphate at the P(1) site, and Lys-9 was stabilized by hydrogen bonds, contributed by Pyr-1, Tyr-28, and Asn-38. Thr-70 acts as a hydrogen bond, donor for cytosine through Thr-39 and determines B(1) base specificity., Interestingly, Pyr-1 along with Lys-95 and Glu-97 form four hydrogen bonds, with guanine at B(2) site and determine B(2) base specificity.

About this Structure

1M07 is a Single protein structure of sequence from Rana catesbeiana. Active as Pancreatic ribonuclease, with EC number 3.1.27.5 Full crystallographic information is available from OCA.

Reference

Residues involved in the catalysis, base specificity, and cytotoxicity of ribonuclease from Rana catesbeiana based upon mutagenesis and X-ray crystallography., Leu YJ, Chern SS, Wang SC, Hsiao YY, Amiraslanov I, Liaw YC, Liao YD, J Biol Chem. 2003 Feb 28;278(9):7300-9. Epub 2002 Dec 23. PMID:12499382

Page seeded by OCA on Tue Nov 20 21:01:42 2007