1ld6
From Proteopedia
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STRUCTURE OF BPTI_8A MUTANT
Overview
Here we determined NMR solution structures of two mutants of bovine, pancreatic trypsin inhibitor (BPTI) to reveal structural reasons of their, decreased thermodynamic stability. A point mutation, A16V, in the, solvent-exposed loop destabilizes the protein by 20 degrees C, in contrast, to marginal destabilization observed for G, S, R, L or W mutants. In the, second mutant introduction of eight alanine residues at, proteinase-contacting sites (residues 11, 13, 17, 18, 19, 34, 37 and 39), provides a protein that denatures at a temperature about 30 degrees C, higher than expected from additive behavior of individual mutations. In, order to efficiently determine structures of these variants, we applied a, procedure that allows us to share data between regions unaffected by, mutation(s). NOAH/DYANA and CNS programs were used for a rapid assignment, of NOESY cross-peaks, structure calculations and refinement. The solution, structure of the A16V mutant reveals no conformational change within the, molecule, but shows close contacts between V16, I18 and G36/G37. Thus, the, observed 4.3kcal/mol decrease of stability results from a strained local, conformation of these residues caused by introduction of a beta-branched, Val side-chain. Contrary to the A16V mutation, introduction of eight, alanine residues produces significant conformational changes, manifested, in over a 9A shift of the Y35 side-chain. This structural rearrangement, provides about 6kcal/mol non-additive stabilization energy, compared to, the mutant in which G37 and R39 are not mutated to alanine residues.
About this Structure
1LD6 is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
Reference
NMR structures of two variants of bovine pancreatic trypsin inhibitor (BPTI) reveal unexpected influence of mutations on protein structure and stability., Cierpicki T, Otlewski J, J Mol Biol. 2002 Aug 23;321(4):647-58. PMID:12206780
Page seeded by OCA on Tue Nov 20 20:29:31 2007
