5cha
From Proteopedia
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THE REFINEMENT AND THE STRUCTURE OF THE DIMER OF ALPHA-*CHYMOTRYPSIN AT 1.67-*ANGSTROMS RESOLUTION
Overview
The two molecules of the asymmetric unit of the pH 3.5 conformer of, alpha-chymotrypsin have been refined at 1.67-A resolution using restrained, least squares methods with Hendrickson's program (PROLSQ). The final R, factor is 0.179 (including 247 water molecules). The folding of the main, chain of the independent molecules is the same within experimental error, but the same does not generally apply to the side chain stereochemistry., From this we conclude that the folding of a protein structure is basically, independent of most of the detailed stereochemistry of its side chains., The side chains of the interface region between the independent molecules, display pronounced asymmetry. This asymmetry suggests that dynamic and, asymmetrical structural changes take place at the time of oligomerization, leading to more energetically favorable interactions for the dimer., Comparison of the structures of the independent molecules of, alpha-chymotrypsin with the structure of monomeric gamma-chymotrypsin, revealed that although the folding of the three molecules is essentially, the same, numerous and significant differences pervade the side chain, stereochemistry attributable to general flexibility. The specificity site, of alpha-chymotrypsin is occupied by ordered water molecules in a similar, way to gamma-chymotrypsin and other proteins. Some of these water, molecules are displaced when substrate binds to the enzyme, while the, others appear to help identify and position the aromatic side chain in, catalysis.
About this Structure
5CHA is a Protein complex structure of sequences from Bos taurus. This structure superseeds the now removed PDB entry 3CHA. Active as Chymotrypsin, with EC number 3.4.21.1 Full crystallographic information is available from OCA.
Reference
The refinement and the structure of the dimer of alpha-chymotrypsin at 1.67-A resolution., Blevins RA, Tulinsky A, J Biol Chem. 1985 Apr 10;260(7):4264-75. PMID:3980476
Page seeded by OCA on Tue Nov 20 19:25:59 2007
