Isolation and Structural Identification of a New Cross-linking Amino Acid, Allodesmosine, from the Acid Hydrolysate of Elastin

A new polyfunctional cross-linking amino acid was isolated from the hydrolysate of bovine ligamentum nuchae elastin. This compound was a very hygroscopic, white amorphous solid with a faint yellow tinge, and was soluble in aqueous solvents but not in dry methanol. Its proposed structure was verified by ultraviolet spectroscopy, fast atom bombardment mass spectroscopy, and 1H- and 13C-nuclear magnetic resonace spectroscopy. The data indicated it to be a pentafunctional amino acid with a quaternary pyridinium structure similar to desmosine. The mass spectral analysis indicated a parent compound with a mass of 655 (C30H51N6O10). The proposed structure is one derived from the condensation of one lysine residue and four allysine residues. Based on the names of other cross-linking amino acids found in elastin, the trivial name of allodesmosine is given for this compound. Allodesmosine was also detected in hydrolysates of bovine lung, aorta and skin by high-performance liquid chromatography.