Abstract
Experimental atherosclerosis using rabbits was prepared to examine the difference between normal aorta and atherosclerotic aorta. In contrast to elastin in normal aorta, there were marked changes in amino acid composition and structure of elastin in atherosclerotic aorta, and the accumulations of calcium and lipids on the denatured elastin were observed in the less-elastic aorta of atherosclerosis. Elastin, the core protein of elastic fibers, contains repeating peptide sequences such as tetrapeptide, pentapeptide and hexapeptide in the hydrophobic regions. Polypeptides and cross-linked polypeptides were synthesized as model peptides for these repeating peptide seqnences by a chemical method or an irradiation method (60Co), and the functions of these synthetic peptides were examined. A coacervation process of the polypentapeptide was completely reversible. The cross-linked polypentapeptide was an elastomer and showed elastic modnlus similar to that of aortic elastic fibers, whereas the other cross-linked polypeptides were slightly elastomeric or nonelastomeric. The elastomeric force of this cross-linked polypentapeptide was dependent on the ionic strength and was developed by adding the salts. Furthermore the elatomeric force of the cross-linked polypentapeptide containing glutamic acid was developed at pH2.1 (around isoelectric point) and turned off at pH7.4.
