Characterization of two high molecular weight catechol-containing glycoproteins from pharate pupal cuticle of the tobacco hornworm, Manduca sexta☆

摘要: Two high molecular weight cuticular proteins (MSCP120 and MSCP246) were extracted in acidic guanidine hydrochloride solution from tanning abdominal cuticle of Manduca sexta pharate pupae purified by size exclusion performance liquid chromatography. The apparent weights ca. 120 246 kDa as determined sodium dodecyl sulfate polyacrylamide gel electrophoresis. Both contained levels glutamate/glutamine, glycine, serine, alanine aspartate/asparagine. MSCP120 was enriched histidine relative to MSCP246, but the reverse true for valine proline. Small quantities β-alanine 3,4-dihydroxyphenylalanine (DOPA), well other catechols carbohydrates, also detected hydrolysates. became radiolabeled when [1-14C]-β-alanine injected into pupae, presumably formation adducts with N-β-alanyldopamine metabolites during sclerotization. Mild acid hydrolysis released N-β-alanylnorepinephrine 3,4-dihydroxyphenylketoethanol both proteins. Strong yielded predominantly 3,4-dihydroxyphenylketoethylamine (arterenone), DOPA dopamine. N-terminal amino sequences two dissimilar, that MSCP246 more hydrophobic than MSCP120. these glycosylated glucose, N-acetylglucosamine traces N-acetylgalactosamine, galactose. These structural glycoproteins, which occur undergoing sclerotization, apparently react post-translationally quinonoid agents yield catecholamine-protein adducts. amounts peptidyl probably are formed hydroxylation tyrosyl residues. Results this study consistent hypothesis catechol-containing glycoproteins participate cross-linking reactions M. pupal