Studies on the free amino acids and related compounds in the tissues of the cat.

The present study has been undertaken to obtain information on the amino acids and related compounds of animal tissues by the chromatographic analysis of protein-free extracts on columns of sulfonated polystyrene resins (2). The nature and quantity of bound forms of amino acids have been investigated by analysis of the extracts before and after acid hydrolysis. The tissues of the cat were chosen for study in order to combine a general survey with the special objective of obtaining information on the origin and distribution of felinine, a sulfur-containing amino acid recently discovered in cat urine by Westall (3), and 3-methylhistidine (4), recently found to be excreted by man and the cat.