5rnt
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X-RAY ANALYSIS OF CUBIC CRYSTALS OF THE COMPLEX FORMED BETWEEN RIBONUCLEASE T1 AND GUANOSINE-3',5'-BISPHOSPHATE
OverviewOverview
The complex formed between ribonuclease T1 (RNase T1) and, guanosine-3',5'-bisphosphate (3',5'-pGp) crystallizes in the cubic space, group I23 with alpha = 86.47 (4) A. X-ray data were collected on a, four-circle diffractometer to 3.2 A resolution and the structure was, determined by molecular-replacement methods [ULTIMA; Rabinovich & Shakked, (1984). Acta Cryst. A40, 195-200] based on the RNase T1 coordinates taken, from the complex with guanosine-2'-phosphate. Refinement converged at, 16.6% for 1540 data with Fo greater than 1 sigma (Fo) with acceptable, stereochemistry. The RNase T1 conformation is comparable to that in other, complexes which crystallize preferentially in space group P2(1)2(1)2(1), except for side chains that interact intermolecularly. The guanine of, 3',5'-pGp is bound to the recognition site in the same way as in other, guanine-containing complexes except for its interaction with Glu46. The, side-chain carboxylate of this amino acid does not form hydrogen bonds to, N1H and N2H of guanine but is rotated so as to permit insertion of two, water molecules which replace its acceptor functions. In contrast to other, guanosine derivatives which are bound to RNase T1 in the syn form, 3',5'-pGp is anti. This conformation positions the two phosphate groups, 'outside' the protein, with hydrogen-bonding contacts only to water, molecules; the active site is filled by water. The RNase T1-3',5'-pGp, complex probably has biological significance as it may represent the, enzyme-product complex before dissociation.
About this StructureAbout this Structure
5RNT is a Single protein structure of sequence from Aspergillus oryzae with PGP as ligand. Active as Ribonuclease T(1), with EC number 3.1.27.3 Full crystallographic information is available from OCA.
ReferenceReference
X-ray analysis of cubic crystals of the complex formed between ribonuclease T1 and guanosine-3',5'-bisphosphate., Lenz A, Heinemann U, Maslowska M, Saenger W, Acta Crystallogr B. 1991 Aug 1;47 ( Pt 4):521-7. PMID:1930833
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