Amino Acid Composition of Elastin in the Developing Chick Aorta

Abstract

The presence of a non-collagenous, polar, alkali-soluble protein in intimate association with elastic fibres has been demonstrated by many workers. There have also been reports of apparently extraneous proteins associated with purified elastin, especially from foetal and very young tissues, even after conventional hot alkali treatment. In the present report the amino acid compositions of aortic elastins from foetal and young chicks of various ages indicate that hot alkali-purified elastin is associated with a considerable amount of a more polar protein, the quantity of this second component decreasing with increasing foetal age. The composition of this alkali-resistant component is very similar to that of the protein which is removed by hot alkali extraction. The persistence of this polar, alkali- resistant component suggests that it is not a simple impurity in the elastin, but rather may be an integral part of the newly synthesized foetal elastin molecule.