Cyclopentenosine, major trifunctional crosslinking amino acid isolated from acid hydrolysate of elastin

A trifunctional crosslinking amino acid named cyclopentenosine (CP) was iso lated from the hydrolysate of bovine nuchal ligament elastin. CP and its de rivatives were identified by spectroscopic methods. CP was found to consist of a 2-cyclopenten-1-one structure and its imine-enamine tautomers with en antiomers in H2O. A model reaction for the formation of the CP crosslink us ing model compounds for allysine (propanal) and lysine (n-butylamine) demon strated that CP is composed of 2-cyclopenten-1-one and alpha, beta, gamma, delta-unsaturated aldehyde derived from three allysine residues. An ion-pai red high-performance liquid chromatographic method for the determination of CP was developed. Among various bovine tissues the nuchal ligament had the highest concentration of CP. The age-related changes in the concentration of CP were examined in the aorta from rat (short-lived species) and bovine (long-lived species). The CP content was very low in the newborn rat but in creased markedly with growth. After maturity, the CP content remained nearl y the same or slightly decreased. In bovine aorta, the CP content scarcely changed from 7 months to 16 years. (C) 1999 Academic Press.