2nwy: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:2nwy.jpg|left|200px]] | [[Image:2nwy.jpg|left|200px]] | ||
'''Structural and kinetic effects of hydrophobic mutations on the active site of human carbonic anhydrase II''' | {{Structure | ||
|PDB= 2nwy |SIZE=350|CAPTION= <scene name='initialview01'>2nwy</scene>, resolution 1.65Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=ZN:ZINC ION'>ZN</scene> | |||
|ACTIVITY= [http://en.wikipedia.org/wiki/Carbonate_dehydratase Carbonate dehydratase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.1 4.2.1.1] | |||
|GENE= CA2 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens]) | |||
}} | |||
'''Structural and kinetic effects of hydrophobic mutations on the active site of human carbonic anhydrase II''' | |||
==Overview== | ==Overview== | ||
| Line 10: | Line 19: | ||
==About this Structure== | ==About this Structure== | ||
2NWY is a [ | 2NWY is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2NWY OCA]. | ||
==Reference== | ==Reference== | ||
Speeding up proton transfer in a fast enzyme: kinetic and crystallographic studies on the effect of hydrophobic amino acid substitutions in the active site of human carbonic anhydrase II., Fisher SZ, Tu C, Bhatt D, Govindasamy L, Agbandje-McKenna M, McKenna R, Silverman DN, Biochemistry. 2007 Mar 27;46(12):3803-13. Epub 2007 Mar 2. PMID:[http:// | Speeding up proton transfer in a fast enzyme: kinetic and crystallographic studies on the effect of hydrophobic amino acid substitutions in the active site of human carbonic anhydrase II., Fisher SZ, Tu C, Bhatt D, Govindasamy L, Agbandje-McKenna M, McKenna R, Silverman DN, Biochemistry. 2007 Mar 27;46(12):3803-13. Epub 2007 Mar 2. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17330962 17330962] | ||
[[Category: Carbonate dehydratase]] | [[Category: Carbonate dehydratase]] | ||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
| Line 24: | Line 33: | ||
[[Category: proton transfer]] | [[Category: proton transfer]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 17:52:13 2008'' | ||
Revision as of 18:52, 20 March 2008
| |||||||
| , resolution 1.65Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | |||||||
| Gene: | CA2 (Homo sapiens) | ||||||
| Activity: | Carbonate dehydratase, with EC number 4.2.1.1 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Structural and kinetic effects of hydrophobic mutations on the active site of human carbonic anhydrase II
OverviewOverview
Catalysis of the hydration of CO2 by human carbonic anhydrase isozyme II (HCA II) is sustained at a maximal catalytic turnover of 1 mus-1 by proton transfer between a zinc-bound solvent and bulk solution. This mechanism of proton transfer is facilitated via the side chain of His64, which is located 7.5 A from the zinc, and mediated via intervening water molecules in the active-site cavity. Three hydrophilic residues that have previously been shown to contribute to the stabilization of these intervening waters were replaced with hydrophobic residues (Y7F, N62L, and N67L) to determine their effects on proton transfer. The structures of all three mutants were determined by X-ray crystallography, with crystals equilibrated from pH 6.0 to 10.0. A range of changes were observed in the ordered solvent and the conformation of the side chain of His64. Correlating these structural variants with kinetic studies suggests that the very efficient proton transfer (approximately 7 micros-1) observed for Y7F HCA II in the dehydration direction, compared with the wild type and other mutants of this study, is due to a combination of three features. First, in this mutant, the side chain of His64 showed an appreciable inward orientation pointing toward the active-site zinc. Second, in the structure of Y7F HCA II, there is an unbranched chain of hydrogen-bonded waters linking the proton donor His64 and acceptor zinc-bound hydroxide. Finally, the difference in pKa of the donor and acceptor appears favorable for proton transfer. The data suggest roles for residues 7, 62, and 67 in fine-tuning the properties of His64 for optimal proton transfer in catalysis.
DiseaseDisease
Known disease associated with this structure: Osteopetrosis, autosomal recessive 3, with renal tubular acidosis OMIM:[611492]
About this StructureAbout this Structure
2NWY is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
Speeding up proton transfer in a fast enzyme: kinetic and crystallographic studies on the effect of hydrophobic amino acid substitutions in the active site of human carbonic anhydrase II., Fisher SZ, Tu C, Bhatt D, Govindasamy L, Agbandje-McKenna M, McKenna R, Silverman DN, Biochemistry. 2007 Mar 27;46(12):3803-13. Epub 2007 Mar 2. PMID:17330962
Page seeded by OCA on Thu Mar 20 17:52:13 2008