THE AMINO-ACID-COMPOSITION OF CAT (FELIS-CATUS) HAIR

The amino acid composition of cat hair was determined by conventional 24-h acid hydrolysis and non-linear least-squares extrapolation to tim e zero of the amino acid composition data from a series of hydrolysis intervals. Twenty-five individual samples of cat hair, consisting of f our colours, were also analysed (24-h hydrolysis) to determine if ther e was an effect of hair colour on amino acid composition. Amino acids were determined following HCl hydrolysis (6 mol/l) with cysteine and m ethionine determined by performic acid oxidation of the sample prior t o hydrolysis. There was no significant (P > 0.05) effect of hair colou r on the amino acid composition of cat hair. The non-linear compartmen tal model used to determine the amino acid composition of cat hair too k into account the simultaneously occurring processes of hydrolysis an d degradation of amino acids over time. The amino acids cysteic acid, methionine-sulphone, threonine and serine exhibited high loss rates du ring 6 mol/l HCl hydrolysis while the peptide bonds involving valine a nd leucine were slowly hydrolysed. Amino acid nitrogen accounted for 0 .94 of the fetal nitrogen in cat hair when determined by conventional 24-h hydrolysis and 0.99 of the total nitrogen when the compartmental model was applied. The average nitrogen proportion in cat hair protein was found to be 0.175. The amino acid composition of cat hair protein is comparable with that of dog, horse, sheep and human hair although the proline content of cat hair protein appears to be lower than that in the other species.