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

Intima-media of porcine thoracic aorta were digested with pronase, after extraction of the saline-soluble matters and fat. A glycopeptide fraction was precipitated with 90% (vol/vol) ethanol from the 80% ethanol-soluble fraction of the trichloroacetic acid (7%)-soluble fraction of the pronase digest. The glycopeptide fraction was fractionated by affinity chromatography on concanavalin A (Con A)-Sepharose 4B, yielding 4 fractions (FA, FB, FC and FD). The most carbohydrate-rich fraction (FB) was further purified to a homogeneous state. The purified FB (FB-0.1) and all other fractions contained desmosine and isodesmosine. The major sugars in the fractions without or with low affinity for Con A (FA, FB, and FB-0.1) were glucosamine, galactose, mannose and sialic acid, while those in the fractions with high affinity for this lectin (FC and FD) were glucosamine, glucose and mannose. All the fractions contained glycine, aspartic acid (and/or asparagine), serine, proline, threonine, glutamic acid (and/or glutamine) and alanine as the major amino acids, amounting to approximately 80% of the total.