Primary structure of human carbonic anhydrase C

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Human erythrocyte carbonic anhydrase C is a vital enzyme.
• Understanding its primary structure is key to its function.

Purpose of the Study:

• To determine the complete amino acid sequence of human erythrocyte carbonic anhydrase C.
• To investigate potential post-translational modifications like deamidation.

Main Methods:

• Enzyme purification and chemical modification (amidination).
• Limited tryptic digestion to cleave at arginyl bonds.
• Separation and manual sequencing of tryptic fragments.

Main Results:

• The primary structure of human carbonic anhydrase C was elucidated, comprising a 259-residue polypeptide chain without disulfide bridges.
• Three asparagine residues in -Asn-Gly- sequences were identified as prone to deamidation, potentially undergoing a beta-aspartyl shift.
• Minor discrepancies with existing data were noted and discussed.

Conclusions:

• The determined primary structure provides a foundation for understanding carbonic anhydrase C's catalytic mechanism.
• Insights into residue function within the active site were gained through comparison with other carbonic anhydrases.
• The identification of deamidation-prone sites offers implications for enzyme stability and function studies.