Chitin-bound protein of sarcophagid larvae: metabolism of covalently linked aromatic constituents.
The borate-insoluble chitin-protein complex, CB-I, from prepupal sarcophagid larvae was cleaved with chymotrypsin and trifluoromethanesulfonic acid releasing a polypeptide fragment of Mr 68 000. The intact glycoprotein was blocked at the C terminus; the N-terminal sequence of Asp-Val-Ala-His-Tyr was not homologous with seven of the borate-soluble nonglycosylated structural proteins. Bityrosine was identified as a component of the primary chain, both half-residues occupied in peptide linkages. Sclerotization initiated a decline in bityrosine coincident with the addition of soluble proteins to the tanned matrix. The chitin-protein complex also included bound peroxidase, propolyphenol oxidase, and an o-diphenol subject to oxidation on activation of the zymogen. In the course of the oxidation N termini declined in accordance with the formation of 1,4 quinonoid cross-links.
D000595:Amino Acid Sequence; D002686:Chitin / Q000378:metabolism*; D002918:Chymotrypsin / Q000378:metabolism; D004175:Diptera / Q000254:growth & development / Q000378:metabolism*; D006023:Glycoproteins / Q000032:analysis; D007814:Larva / Q000378:metabolism; D008698:Mesylates / Q000378:metabolism; D008970:Molecular Weight; D011506:Proteins / Q000378:metabolism*; D012995:Solubility
D006023:Glycoproteins; D008698:Mesylates; D011506:Proteins; D002686:Chitin; D002918:Chymotrypsin; C012077:trifluoromethanesulfonic acid