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[ccp4bb] Activity of a mutant enzyme compared to wild type - puzzle |
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CCP4bb navigationCCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999Subject: Activity of a mutant enzyme compared to wild type - puzzle From: Narayanan Ramasubbu ramasun1 {- at -} UMDNJ {- dot -} EDU Date: 2008-06-12 Dear all: I have a single residue mutant whose enzyme activity is about 50% of the wild type. Interestingly, the mutation is in a region that involves a secondary site but not the active site. The two structures with or without ligands fit well (0.18 A) and the metal binding and cofactor binding sites are all preserved in the mutant. The one difference noticed is that the ligand does not fill the active site (partially occupied subsites) unlike the wild type where all the subsites are occupied. Water structure around the actives site residues are "identical". I looked at the electrostatics and both surfaces look similar (not an expert). There are some residues whose sides chains show some positional disorder and these residues are at the edges of the active site. The resolution of the both data sets are 1.5A. The mutant enzyme was derived by MR. One another possibility that I want to look at is to compare the compactness of the two enzyme structures. What is the best way to compare that? I am wondering whether the "breathing" that was mentioned for some enzymes might be playing a role in the mutant enzyme. Also, I would appreciate comments on other possible explanations for this unusual (?) behavior. Thanks a lot Subbu CCP4bb navigationCCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999 |
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