Preparation and Properties of Salt-soluble Elastin

Abstract

Abstract Salt-soluble elastin was extracted from the aortas of copper-deficient pigs and purified to homogeneity as judged by ultracentrifugation, disc electrophoresis, and amino acid analysis. Purification took advantage of the differing solubilities of glycoproteins, salt-soluble collagen, and salt-soluble elastin in salt solutions of differing ionic strength, pH, and temperature. The amino acid composition of this protein is like that of insoluble elastin with the exceptions of a higher lysine content and the absence of cross-linking amino acids in the former. Analyses excluded the presence of α-amino adipic δ-semialdehyde, neutral sugars, glucosamine, galactosamine, tryptophan, cysteine, cystine, methionine, and histidine. The protein exhibits cationic behavior during electrophoresis at pH 8.9, consistent with its content of lysine as the predominant polar amino acid. Salt-soluble elastin has a subunit molecular weight of 74,000 as judged by sedimentation equilibrium in 6 m guanidine-mercaptoethanol. It is proposed that this protein is a precursor of insoluble elastin.