Carnosine and related substances in animal tissues

1. The occurrence of carnosine, anserine, ophidine, β-alanine, γ-aminobutyric acid, histidine, 1-methylhistidine and 3-methylhistidine in the muscle tissues of twenty-six vetebrate species and the skins of two reptiles was studied using paper chromatography. 2. One or two of the dipeptides was found in each tissue. Some tissues also contained β-alanine and histidine, but γ-aminobutyric acid, 1-methylhistidine and 3-methylhistidine were not detected. 3. Relationships appear to exist between the zoological classification of a species and the identities and relative amounts of its dipeptides. 4. The reptile skins contained the same dipeptides and other substances as their corresponding muscle tissues. 5. Biochemical and biological information about the dipeptides is discussed.