Molecular characterization of the human carbonic anhydrase-related protein (HCA-RP VIII)

• Published in: Biochimica et biophysica acta 1998-05, Vol.1384 (2), p.294-298
• Main Authors: Bergenhem, Nils C.H, Hallberg, Martina, Wisén, Susanne
• Format: Article
• Language: English
• Subjects: Biomarkers, Tumor; Carbonic anhydrase; Carbonic Anhydrases - chemistry; Carbonic Anhydrases - isolation & purification; Carbonic Anhydrases - metabolism; Circular Dichroism; Escherichia coli - genetics; Guanidine hydrochloride; Humans; Molecular weight; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - isolation & purification; Protein Denaturation; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Unfolding
• ISSN: 0167-4838; 0006-3002; 1879-2588
• DOI: 10.1016/S0167-4838(98)00020-X

The very evolutionarily conserved human carbonic anhydrase-related polypeptide (CA-RP VIII) lacks the carbon-dioxide hydration-activity, characteristic of the enzymatically active carbonic anhydrases. We have expressed HCA-RP VIII as a glutathione- S-transferase fusion protein (GST-HCA-RP VIII). The purified HCA-RP VIII showed a substantially higher apparent molecular weight by gel-filtration compared to the molecular weight calculated from the amino acid sequence, indicating a larger than expected Stoke's radius. Like other studied CA's, the protein unfolds through two transitions at increasing concentrations of guanidine hydrochloride. The far-UV CD spectra of HCA-RP VIII indicates a secondary structure similar to that of the catalytically active HCA II. The very high sequence identity between human and mouse CA-RP VIII (98%), might indicate that the function of the protein involves binding of another protein. However, an attempt to use the GST-HCA-RP VIII fusion protein to affinity purify a ligand was unsuccessful.