Sulfated glycopeptides, containing desmosine and isodesmosine, isolated from porcine aorta

Intima-media of porcine thoracic aorta was digested with pronase, after extraction of saline-soluble matters and fat. A crude sulfated glycopeptide fraction (CSGP) was precipitated with 90% (v/v) ethanol from the 80% ethanol-soluble fraction of the trichloroacetic acid (7%)-soluble fraction of the pronase digest. CSGP was fractionated by DEAE-Sephadex A-25 (Cl- form) column chromatography. Of the resulting 9 fractions, 4 major fractions were further purified by gel filtration on Sephadex G-50, followed by affinity chromatography on concanavalin (Con) A-Sepharose 4B to a homogeneous state in electrophoresis on cellulose acetate membrane. All the purified fractions contained glucosamine, galactose, mannose, and sialic acid as the major sugars, and desmosine and isodesmosine as the unique constituents. The fractions with affinity for Con A (S1 and S2) contained much more mannose than those without affinity for this lectin (S3 and S4). The latter contained sulfate. The predominant amino acids in the former were glycine, aspartic acid (and/or asparagine), and serine, while those in the latter were glycine, proline, and alanine.