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Characterization of CA XIII, a novel member of the carbonic anhydrase isozyme family.

Author

  • Jonna Lehtonen
  • Bairong Shen
  • Mauno Vihinen
  • Angela Casini
  • Andrea Scozzafava
  • Claudiu T Supuran
  • Anna-Kaisa Parkkila
  • Juha Saarnio
  • Antti J Kivelä
  • Abdul Waheed
  • William S Sly
  • Seppo Parkkila

Summary, in English

The carbonic anhydrase (CA) gene family has been reported to consist of at least 11 enzymatically active members and a few inactive homologous proteins. Recent analyses of human and mouse databases provided evidence that human and mouse genomes contain genes for still another novel CA isozyme hereby named CA XIII. In the present study, we modeled the structure of human CA XIII. This model revealed a globular molecule with high structural similarity to cytosolic isozymes, CA I, II, and III. Recombinant mouse CA XIII showed catalytic activity similar to those of mitochondrial CA V and cytosolic CA I, with k(cat)/K(m) of 4.3 x 10(7) m(-1) s(-1), and k(cat) of 8.3 x 10(4) s(-1). It is very susceptible to inhibition by sulfonamide and anionic inhibitors, with inhibition constants of 17 nm for acetazolamide, a clinically used sulfonamide, and of 0.25 microm, for cyanate, respectively. Using panels of cDNAs we evaluated human and mouse CA13 gene expression in a number of different tissues. In human tissues, positive signals were identified in the thymus, small intestine, spleen, prostate, ovary, colon, and testis. In mouse, positive tissues included the spleen, lung, kidney, heart, brain, skeletal muscle, and testis. We also investigated the cellular and subcellular localization of CA XIII in human and mouse tissues using an antibody raised against a polypeptide of 14 amino acids common for both human and mouse orthologues. Immunohistochemical staining showed a unique and widespread distribution pattern for CA XIII compared with the other cytosolic CA isozymes. In conclusion, the predicted amino acid sequence, structural model, distribution, and activity data suggest that CA XIII represents a novel enzyme, which may play important physiological roles in several organs.

Publishing year

2004

Language

English

Pages

2719-2727

Publication/Series

Journal of Biological Chemistry

Volume

279

Issue

4

Document type

Journal article

Publisher

American Society for Biochemistry and Molecular Biology

Topic

  • Medical Genetics

Keywords

  • Carbonic Anhydrases: analysis
  • Carbonic Anhydrases: genetics
  • Carbonic Anhydrases: metabolism
  • Isoenzymes: analysis
  • Isoenzymes: genetics
  • Isoenzymes: metabolism

Status

Published

ISBN/ISSN/Other

  • ISSN: 1083-351X