1ugc
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| , resolution 2.0Å | |||||||
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| Ligands: | , | ||||||
| Gene: | CAII (Homo sapiens) | ||||||
| Activity: | Carbonate dehydratase, with EC number 4.2.1.1 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
HUMAN CARBONIC ANHYDRASE II [HCAII] (E.C.4.2.1.1) MUTANT WITH ALA 65 REPLACED BY HIS (A65H)
OverviewOverview
The three-dimensional structures of A65F, A65L, A65H, A65T, A65S, and A65G human carbonic anhydrase II (CAII) variants have been solved by X-ray crystallographic methods to probe the importance of residue 65 and the structural implications of its evolutionary drift in the greater family of carbonic anhydrase isozymes. Structure-activity relationships in this series of CAII variants are correlated with those established for other carbonic anhydrase isozymes. We conclude that a bulky side chain at position 65 hinders the formation of an effective solvent bridge between zinc-bound water and H64 and thereby hinders solvent-mediated proton transfer between these two groups [Jackman, J. E., Merz, K. M., Jr., & Fierke, C. A. (1996) Biochemistry 35, 16421-16428]. Despite the introduction of a polar hydroxyl group at this position, smaller side chains such as serine or threonine substituted for A65 do not perturb the formation of a solvent bridge between H64 and zinc-bound solvent. Thus, the evolution of residue 65 size is one factor affecting the trajectory of catalytic proton transfer.
About this StructureAbout this Structure
1UGC is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
X-ray crystallographic studies of alanine-65 variants of carbonic anhydrase II reveal the structural basis of compromised proton transfer in catalysis., Scolnick LR, Christianson DW, Biochemistry. 1996 Dec 24;35(51):16429-34. PMID:8987974
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