The amino acid composition of collagen or gelatin from five species of mammals (man, ox, pig, whale and wallaby) has been determined by ion exchange chromatography.
The results obtained for ox-hide gelatin are in good agreement with previously published values, except for alanine and serine.
The composition of gelatin is closely similar to that of the collagen preparations, suggesting that gelatin is representative of the main protein constituent of collagenous tissues in amino acid composition.
The collagen of the land placentals studied did not show any marked variation between species.The content of serine and threonine in whale gelatin exceeded that in land mammals, but was not so high as that from other classes of marine vertebrates. Wallaby collagen also contained very slightly higher amounts of serine and threonine than the other land mammals.
Gelatin contained less tyrosine than the collagenous precursors. Fractionation of gelatin with ethanol to remove impurities led to a further reduction in tyrosine content. It has not yet been proved that tyrosine is a true constituent of gelatin.