Rapid Degradation of the Silkworm Diapause Hormone by Trypsin and Its Suppression by VAP-map, a Synthetic Analog of the Cuticular Peptide of Silkworm, Bm ACP-6.7 (VAP-Peptide)

Abstract

Very fast tryptic degradation of the silkworm diapause hormone was found and the degradation pathway was analyzed by moderating the reaction conditions. It proceeded via cleavage at Arg²³ and finally at Arg¹⁵ of DH. As the C-terminal structure of DH was essential for exhibiting bioactivity, the first cleavage caused rapid inactivation of the hormone. This tryptic digestion was strongly suppressed by adding VAP-map, a synthetic analog of the cuticular peptide of silkmoths, Bm ACP-6.7 (VAP-peptide), which is a natural synergist of DH. VAP-map suppressed the enzymic reaction by interacting with the substrate, but not with the enzyme.