Carnosine
Carnosine is a naturally occurring dipeptide composed of beta-alanine and L-histidine, functioning as an intracellular pH buffer, antioxidant, and anti-glycation agent in muscle and brain tissue.
Chemical Identity
| Property | Value |
|---|---|
| Chemical Formula | C6H9N3O3 |
| Molecular Weight | 226.23 g/mol |
| CAS Number | 305-84-6 |
| IUPAC Name | (2S)-2-[(3-aminopropanoyl)amino]-3-(1H-imidazol-4-yl)propanoic acid |
| Peptide Class | Dipeptide |
| Amino Acid Composition | beta-Ala-His |
Structure
Carnosine is a dipeptide formed by a peptide bond linking the amino group of beta-alanine to the carboxyl group of L-histidine. Unlike standard alpha-amino acids, beta-alanine lacks an alpha-amino group, giving carnosine its distinctive structural characteristics. The imidazole ring of histidine is responsible for many of carnosine’s biochemical properties, including its pH-buffering capacity in the physiological range.
Physiological Functions
Intracellular pH Buffering
Carnosine is present at high concentrations in skeletal muscle, where it serves as a critical intracellular buffer against exercise-induced acidosis. The imidazole ring has a pKa near 6.8, placing its buffering range close to physiological pH. During high-intensity exercise, carnosine accepts protons as lactic acid accumulates, helping maintain intracellular pH and sustaining muscle contraction.
Antioxidant Activity
Carnosine scavenges reactive oxygen species (ROS) including hydroxyl radicals, singlet oxygen, and superoxide anions. It also chelates transition metal ions such as copper and iron, preventing Fenton chemistry-mediated oxidative damage.
Anti-Glycation
Carnosine inhibits the formation of advanced glycation end-products (AGEs) by reacting with reactive carbonyl species before they can modify proteins. This property has implications for diabetic complications and aging research.
Tissue Distribution
Carnosine is synthesized in skeletal muscle by carnosine synthase and is found at concentrations up to 30 mM in fast-twitch muscle fibers. It is also present in the central nervous system, cardiac muscle, and renal tissue. Dietary sources include red meat and poultry.
References
- Soldi, M., Bhatt, S., & Bhatt, D.L. (2024). Cellular Signalling. DOI: 10.1016/j.cellsig.2023.110601
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