Evidence for Glycosylated Crosslinks in Body-Wall Collagen of the Sea Cucumber,Thyone briareus

Summary

Only one tritiated compound, the reduced crosslink hydroxylysinohydroxy-norleucine, is detected by ion-exchange chromatography after [³H]-NaBH₄ reduction and acid hydrolysis of body-wall collagen from the sea cucumber, Thyone briareus. However, after hydrolysis of the [³H]-NaBH₄-treated collagen in 2 M KOH rather than in acid, much less of this compound is detected. Instead, a new main peak of ³H-activity is eluted earlier, near tyrosine. The compound in this new peak could be converted to hydroxylysinohydroxynorleucine by hydrolysis in 2 M HCl, or to an intermediate compound by hydrolysis in 0.1 M HCl. About equal amounts of glucose and galactose were detected by thin-layer chromatography after hydrolysis of the isolated compound with the higher concentration of acid. It is concluded that in this invertebrate collagen most of the crosslink, dehydro-hydroxylysinohydroxynorleucine, is glycosylated. Since the reduced form of the crosslink could not be detected by reaction with Ninhydrin in large samples of the collagen, reduction of dehydro-hydroxylysino-hydroxynorleucine to hydroxylysinohydroxy-norleucine in vivo does not appear to be a significant pathway for the maturation of crosslinks in body-wall collagen of Thyone briareus.

Fig. 2. Chromatographic analysis of the crosslink, HylOHNle, in body wall collagen of sea cucumber hydrolyzed in 6 M HCl for 24 hr at 105°. Upper-NaBH₄-treated tissue. Lower—untreated tissue.

This study was supported in part by a Grant from the National Institutes of Health (AM 15671).