Abstract: Esterase A4（EA4）, a time interval measuring enzyme in the diapausing eggs of Bombyx mori, was isolated and purified from C108 silkworm diapausing eggs and acid-treated eggs 2 days after oviposition, respectively. The PIN is a kind of peptide inhibitory needle for EA4 enzyme activity. Its amino acid sequence is SIFMTKQHSQ DDIIQHPLDY VEQQIHQQKQ KLQKQTLN. The action of PIN on EA4 was studied in the paper. When the enzymic protein EA4 from diapausing eggs was incubated with the synthetic PIN for 24 h at 25℃, a complex of EA4 and PIN was detected by matrix-assisted laser desorption ionization mass spectrometry. When the treated mixture above was incubated again in 2.5% HCl, the complex could not be found. There is no complex formed when the EA4 protein from acid-treated eggs was incubated with the synthetic PIN. At 25℃ in vitro, the activity peak of EA4 from diapausing eggs and acid-treated eggs for ATPase appeared at 6.5 h and 1.5 h, respectively. The results showed that the activation of diapausing eggs was due to eliminating the inhibition of PIN on EA4 and activating EA4 by HCl within a short time.

Key words: Bombyx mori, diapause, hydrochloric acid\|treatment, esterase A4, target