Peptides Obtained From Elastin by Hydrolysis with Aqueous Ethanolic Potassium Hydroxide

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Abstract
Elastin from bovine ligamentum nuchae was hydrolyzed with 1 M KOH in 80% ethanol at 37°C for 0.5 to 72 h. Sephadex G 100 gel filtration separated the coacervable fractions from the retarded peptides (MW: 16,000) unable to form coacervates. Their ratio changed with progressing hydrolysis. The maximal yield fo coacervable peak was obtained after hydrolysis for about 6 h, whereas after hydrolysis from 18 to 72 h, only a nonco-acervable peak was recovered. The noncoacervable Sephadex peak was eluted at an identical position after hydrolysis for 4 and 72 h with an apparent molecular weight of 16,000 dalton on polyacrylamide SDS gel electrophoresis. The noncoacervable Sephadex peaks (MW: 16,000) obtained after hydrolysis for 4 and 72 h were submitted to isoelectric focusing in Servalyt in the pH range 2.5-11. The major crosslinked peptides were refocused in the pH range 2.5-6. In the major purified crosslinked peptides, recovered after hydrolysis for 4 h, the Ala to Gly ratio (1:1) was similar to that found in elastin. The minor component lacking desmosines is rich in Ala, Pro and Gly. In the crosslinked peptides separated after hydrolysis for 72 h, the ratio of Ala to Gly is 2:1 and their desmosine content is about 2.5 times higher than in elastin. The resistance of elastin peptides to hydrolysis with ethanolic KOH appears to be related to their high Ala and Des content.