1mua
From Proteopedia
STRUCTURE AND ENERGETICS OF A NON-PROLINE CIS-PEPTIDYL LINKAGE IN AN ENGINEERED PROTEIN
Overview
The crystal structure of a human carbonic anhydrase II (CAII) variant, cis-proline-202-->alanine (P202A), has been determined at 1.7-A resolution, indicating that the wild-type geometry, including the cis-peptidyl linkage, is retained upon substitution of proline by alanine. The CO2 hydrase activity and affinity for sulfonamide inhibitors of P202A CAII are virtually identical to those of wild type. However, the substitution of cis-alanine for cis-proline decreases the stability of the folded state by approximately 5 kcal mol-1 relative to both the unfolded state and an equilibrium intermediate in guanidine hydrochloride-induced denaturation. This destabilization can be attributed mainly to the less favorable cis/trans equilibrium of Xaa-alanine bonds compared to Xaa-proline bonds in the denatured state although other factors, including increased conformational entropy of the denatured state and decreased packing interactions in the native state, also contribute to the observed destabilization. The high catalytic activity of P202A CAII illustrates that unfavorable local conformations are nonetheless endured to satisfy the precise structural requirements of catalysis and ligand binding in the CAII active site.
About this Structure
1MUA is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structure and energetics of a non-proline cis-peptidyl linkage in a proline-202-->alanine carbonic anhydrase II variant., Tweedy NB, Nair SK, Paterno SA, Fierke CA, Christianson DW, Biochemistry. 1993 Oct 19;32(41):10944-9. PMID:8218160 Page seeded by OCA on Sat May 3 01:43:16 2008
