Human carbonic anhydrases and carbonic anhydrase deficiencies
1Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, Missouri 63104, USA.
Abstract:
Carbonic anhydrases (CAs I-VII) are products of a gene family that encodes seven isozymes and several homologous, CA- related proteins. All seven isozymes have been cloned, sequenced, and mapped, and the intron-exon organization of five genes established. They differ in subcellular localizations, being cytoplasmic (CA I, II, III, and VII), GPI-anchored to plasma membranes of specialized epithelial and endothelial cells (CA IV), in mitochondria (CA V), or in salivary secretions (CA VI). They also differ in kinetic properties, susceptibility to inhibitors, and tissue-specific distribution. Structural and kinetic studies of recombinant natural and mutant CAs have greatly increased our understanding of the structural requirements for catalysis. Studies of the effects of CA inhibitors over many years have implicated CAs in a variety of physiological processes. Analyses of human and animal CA deficiencies provide unique opportunities to understand the individual contributions of different isozymes to these processes.
Related Concept Videos
Carbon Dioxide Transport in the Blood
Forms of CO2 Transport
1. Dissolved in plasma: A small percentage (7-10%) of CO2 is transported and dissolved directly in the plasma.
2. Carbaminohemoglobin: Just over 20% of CO2 is chemically bound to...
Renal Tubule and Collecting Duct
Proximal Convoluted Tubule (PCT):
The PCT is the initial segment of the renal tubule, extending from the Bowman's capsule that encloses the glomerulus. Its convoluted structure and microvilli-lined cells increase the surface area for reabsorption. The PCT reabsorbs glucose, amino acids, sodium, and water from the filtrate, ensuring essential...
Roles of Electrolytes: Chloride and Bicarbonate
Conditions such as hypochloremia can arise from insufficient chloride reabsorption by the kidneys, often compounded by extended bouts of diarrhea, vomiting, or...
Bicarbonate-Carbonic Acid Buffer
Diagnosing Acidosis and Alkalosis
First, the pH level is assessed to determine whether the blood pH is normal (7.35–7.45), low (acidosis), or high (alkalosis).
Next, the PCO2 and HCO3− values are examined to...
Acute Respiratory Failure-III


