Elastin Peptides: The Components of a Partial Alkaline Hydrolyzate of Elastin

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Abstract
Bovine ligamentum nuchae elastin was partially hydrolyzed by ethanolic KOH. Fractionation of the dialyzed product on a column of SE-Sephadex yielded eight fractions which were characterized by amino acid analysis as well as hexose and lipid contents. The approximate molecular weight or size range of each of the fractions was determined by Sephadex gel filtration. Study of the amino acid distribution among these fractions revealed the presence of three classes of peptide. The first peak eluted from the SE-Sephadex was found to be a mixture of acidic glyco-peptides, possibly derived from a structural glycoprotein component of elastin. A second type of peptide was represented by the second and third peaks which contained almost exclusively the neutral amino acids glycine, valine and proline. Fraction II was a monodisperse peptide of about 10,000 molecular weight, containing these three amino acids in the approximate ratio of 2:2:1. The third general group of peptide isolated, fractions IV through VIII, was apparently derived from the cross-linked region of elastin. These last five peptides all contain the desmosines in amounts greater than is found in the intact elastin. However, both the desmosine contents (3.1 to 7.8 residues) and the molecular weights (19,000 to over 100,000) were found to vary from fraction to fraction.