The content of dityrosine in chick and rabbit aorta proteins

The possible presence of dityrosine in elastin derived by two different methods and in structural glycoproteins from aortas of 1 day old chicks, adult rabbits and fetal rabbits was determined by a sensitive spectrofluorimetric procedure. Only chick tissues were found to contain dityrosine, 0.3 residues/100,000 total amino acid residues in aortic elastin and 12-15 residues/100,000 residues in the structural glycoproteins. No dityrosine could be detected in any of the fetal or mature rabbit tissues. However, related fluorescent compounds with different excitation-emission maxima and different elution times were obtained by ion exchange chromatography of structural glycoproteins partially hydrolyzed under alkaline conditions.