Carbonic Anhydrase II

Carbonic Anhydrase II: A Vital Enzyme in Maintaining Acid-Base Homeostasis

Carbonic Anhydrase II (CA II) is a crucial enzyme that plays a pivotal role in the regulation of acid-base balance in the human body. Catalyzing the reversible hydration of carbon dioxide (CO2) to carbonic acid (H2CO3), CA II facilitates the transport of CO2 across various tissues and actively participates in maintaining acid-base homeostasis. In this blog, we will explore the key functions, structural characteristics, and notable applications of Carbonic Anhydrase II.

  1. Key Functions:
    1.1 Acid-Base Regulation: CA II is primarily involved in the regulation of the acid-base balance by facilitating the hydration of CO2, which eventually forms bicarbonate ions (HCO3-) and protons (H+). This enzymatic action is essential for maintaining the pH balance in bodily fluids and tissues.

1.2 Gas Exchange: The hydration of CO2 by CA II is necessary for systemic gas exchange in the lungs. By converting CO2 into a soluble form (HCO3-), CA II enables its transport via the bloodstream to the lungs where it is subsequently converted back into CO2 for elimination through exhalation.

1.3 Renal Function: CA II is prominently expressed in the proximal tubules of the kidneys and is responsible for the reabsorption of filtered bicarbonate ions. This reabsorption process significantly contributes to the maintenance of acid-base balance and prevents excessive bicarbonate loss through urine.

  1. Structural Characteristics:
    2.1 Protein Structure: Carbonic Anhydrase II is a zinc metalloenzyme, containing a single metal ion (zinc) per polypeptide chain. The enzyme is predominantly composed of alpha-helices and features an active site where the zinc ion coordinates with water molecules involved in the catalytic reaction.

2.2 Genetic Variants: Several genetic variations in the CA2 gene can alter the structure and function of Carbonic Anhydrase II, leading to potential disruptions in acid-base homeostasis and various disorders such as osteopetrosis and renal tubular acidosis.

2.3 Inhibition and Activation: CA II activity can be influenced by inhibitors and activators, which can be clinically beneficial. For instance, some carbonic anhydrase inhibitors find therapeutic applications in the treatment of glaucoma, edema, and epilepsy.

  1. Applications:
    3.1 Biomedical Research: Carbonic Anhydrase II serves as an important model enzyme for studies related to enzyme kinetics, protein structure, and drug development. The detailed understanding of CA II can have implications on the development of novel treatments for various diseases.

3.2 Clinical Diagnostics: The measurement of CA II in biological fluids can serve as a potential biomarker for various disorders, including cancer, osteoporosis, and kidney dysfunction. Monitoring CA II levels can aid in early diagnosis and treatment of these conditions.

Carbonic Anhydrase II is an indispensable enzyme involved in maintaining acid-base balance, facilitating gas exchange, and supporting renal function. Its structural characteristics and catalytic functions make it a significant target for research and potential therapeutic applications. Understanding the role of Carbonic Anhydrase II can provide valuable insights into human physiology and contribute to the advancement of clinical diagnostics and therapeutic interventions.


  1. Tashian RE. et al., Carbonic Anhydrase II Deficiency Syndrome. 2020 Jan 16. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews®[Internet]. Seattle (WA): University of Washington, Seattle; 1993–2022.
  2. Bruce RK et al., Carbonic Anhydrase: Mechanism, Regulation, Links to Disease, and Industrial Applications, 2016 May 20. Chem Rev. 116(15):7798-813.
  3. Supuran CT, Carbonic Anhydrase Inhibitors – Diversity of Structural Families and Mechanistic Applications, 2016 May 20. Chem Rev. 116(15):7858-89.