9rnt
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RIBONUCLEASE T1 WITH FREE RECOGNITION AND CATALYTIC SITE: CRYSTAL STRUCTURE ANALYSIS AT 1.5 ANGSTROMS RESOLUTION
OverviewOverview
The free form of ribonuclease T1 (RNase T1) has been crystallized at, neutral pH, and the three-dimensional structure of the enzyme has been, determined at 1.5 A nominal resolution. Restrained least-squares, refinement yielded an R value of 14.3% for 12,623 structure amplitudes., The high resolution of the structure analysis permits a detailed, description of the solvent structure around RNase T1, the reliable, rotational setting of several side-chain amide and imidazole groups and, the identification of seven disordered residues. Among these, the, disordered and completely internal Val78 residue is noteworthy. In the, RNase T1 crystal structures determined thus far it is always disordered in, the absence of bound guanosine, but not in its presence. A systematic, analysis of hydrogen bonding reveals the presence in RNase T1 of 40, three-center and an additional seven four-center hydrogen bonds., Three-center hydrogen bonds occur predominantly in the alpha-helix, where, their minor components close 3(10)-type turns, and in beta-sheets, where, their minor components connect the peptide nitrogen and carbonyl functions, of the same residue. The structure of the free form is compared with, complexes of RNase T1 with filled base recognition site and/or catalytic, site. Several structural rearrangements occurring upon inhibitor or, substrate binding are clearly apparent. In conjunction with the available, biochemical knowledge, they are used to describe probable steps occurring, early during RNase T1-catalyzed phosphate transesterification.
About this StructureAbout this Structure
9RNT is a Single protein structure of sequence from Aspergillus oryzae with CA as ligand. Active as Ribonuclease T(1), with EC number 3.1.27.3 Full crystallographic information is available from OCA.
ReferenceReference
Ribonuclease T1 with free recognition and catalytic site: crystal structure analysis at 1.5 A resolution., Martinez-Oyanedel J, Choe HW, Heinemann U, Saenger W, J Mol Biol. 1991 Nov 20;222(2):335-52. PMID:1960730
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