carnosine (beta-alanyl-l-histidine) is a dipeptide molecule, made up of the amino acids beta-alanine and histidine. it is highly concentrated in muscle and brain tissues.[citation needed]

carnosine and carnitine were discovered by russian chemist vladimir gulevich. it has been proven to scavenge reactive oxygen species (ros) as well as alpha-beta unsaturated aldehydes formed from peroxidation of cell membrane fatty acids during oxidative stress. it also buffers ph in muscle cells, and acts as a neurotransmitter in the brain. it is also a zwitterion, a neutral molecule with a positive and negative end.[citation needed]

like carnitine, carnosine is composed of the root word carn, meaning "flesh", alluding to its prevalence in animal protein. there are no plant-based sources of carnosine. therefore, a vegetarian or vegan diet provides little or no carnosine in comparison to the amounts found in a diet that includes meat.

carnosine can chelate divalent metal ions.

carnosine can increase the hayflick limit in human fibroblasts, as well as appearing to reduce the telomere shortening rate. it is also considered as a geroprotector.

biosynthesis
carnosine is synthesized in vivo from beta-alanine and histidine. since beta-alanine is the limiting substrate, supplementing just beta-alanine effectively increases the intramuscular concentration of carnosine.

physiological effects
carnosine has a pka value of 6.83, making it a good buffer for the ph range of animal muscles. since beta-alanine is not incorporated into proteins, carnosine can be stored at relatively high concentrations (millimolar). occurring at 17–25 mmol/kg (dry muscle), carnosine (ß-alanyl-l-histidine) is an important intramuscular buffer, constituting 10-20% of the total buffering capacity in type i and ii muscle fibres.