1rhl
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(New page: 200px<br /><applet load="1rhl" size="450" color="white" frame="true" align="right" spinBox="true" caption="1rhl, resolution 1.95Å" /> '''RIBONUCLEASE T1 COMP...)
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Revision as of 23:29, 20 November 2007
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RIBONUCLEASE T1 COMPLEXED WITH 2'GMP/G23A MUTANT
Overview
Hydrogen-exchange rates were measured for RNase T1 and three variants with, Ala --> Gly substitutions at a solvent-exposed (residue 21) and a buried, (residue 23) position in the helix: A21G, G23A, and A21G + G23A. These, results were used to measure the stabilities of the proteins. The, hydrogen-exchange stabilities (DeltaG(HX)) for the most stable residues in, each variant agree with the equilibrium conformational stability measured, by urea denaturation (DeltaG(U)), if the effects of D(2)O and proline, isomerization are included [Huyghues-Despointes, B. M. P., Scholtz, J. M., and Pace, C. N. (1999) Nat. Struct. Biol. 6, 210-212]. These residues also, show similar changes in DeltaG(HX) upon Ala --> Gly mutations, (DeltaDeltaG(HX)) as compared to equilibrium measurements, (DeltaDeltaG(U)), indicating that the most stable residues are exchanging, from the globally unfolded ensemble. Alanine is stabilizing compared to, glycine by 1 kcal/mol at a solvent-exposed site 21 as seen by other, methods for the RNase T1 protein and peptide helix [Myers, J. K., Pace, C., N., and Scholtz, J. M. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 3833-2837], while it is destabilizing at the buried site 23 by the same, amount. For the A21G variant, only local NMR chemical shift perturbations, are observed compared to RNase T1. For the G23A variant, large chemical, shift changes are seen throughout the sequence, although X-ray crystal, structures of the variant and RNase T1 are nearly superimposable. Ala -->, Gly mutations in the helix of RNase T1 at both helical positions alter the, native-state hydrogen-exchange stabilities of residues throughout the, sequence.
About this Structure
1RHL is a Single protein structure of sequence from Aspergillus oryzae with CA and 2GP as ligands. Active as Ribonuclease T(1), with EC number 3.1.27.3 Full crystallographic information is available from OCA.
Reference
Hydrogen-exchange stabilities of RNase T1 and variants with buried and solvent-exposed Ala --> Gly mutations in the helix., Huyghues-Despointes BM, Langhorst U, Steyaert J, Pace CN, Scholtz JM, Biochemistry. 1999 Dec 14;38(50):16481-90. PMID:10600109
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