title: The active site structure of Thalassiosira weissflogii carbonic anhydrase 1.
abstract: X-ray absorption spectroscopy at the Zn K-edge indicates that the active site of the marine diatom Thalassiosira weissflogii carbonic anhydrase is strikingly similar to that of mammalian alpha-carbonic anhydrase enzymes. The zinc has three histidine ligands and a single water at 1.98 A. This is quite different from the beta-carbonic anhydrases of higher plants in which zinc is coordinated by two cysteine thiolates, one histidine, and a water molecule. The diatom carbonic anhydrase shows no significant sequence similarity with other carbonic anhydrases and may represent an example of convergent evolution at the molecular level.
authors.affiliation: Center for Environmental Bioinorganic Chemistry, Departments of Chemistry and Geosciences, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: E H
authors.initials: EH
authors.lastname: Cox
authors.forename: G L
authors.initials: GL
authors.lastname: McLendon
authors.forename: F M
authors.initials: FM
authors.lastname: Morel
authors.forename: T W
authors.initials: TW
authors.lastname: Lane
authors.forename: R C
authors.initials: RC
authors.lastname: Prince
authors.forename: I J
authors.initials: IJ
authors.lastname: Pickering
authors.forename: G N
authors.initials: GN
authors.lastname: George
mesh_terms: D000818:Animals; D001665:Binding Sites; D002256:Carbonic Anhydrases / Q000737:chemistry* / Q000378:metabolism*; D002417:Cattle; D017377:Diatoms / Q000201:enzymology*; D005583:Fourier Analysis; D012542:Scattering, Radiation; D013057:Spectrum Analysis; D018724:Spinacia oleracea / Q000201:enzymology; D014965:X-Rays; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
chemical_list: D002256:Carbonic Anhydrases; D015032:Zinc