RESUMO
An elastase-like chymotrypsin was purified by aprotinin-agarose affinity chromatography from the midgut extract of cardamom shoot and capsule borer, Conogethes punctiferalis. The purified enzyme had a Vmax of 687.6 +/- 22.1 nmole pNA released/min/mg protein, Km of 0.168 +/- 0.012 mM with SAAPLpNA as substrate and gave a single band on SDS-PAGE with a molecular mass of 72.1 kDa. Casein zymogram revealed one clear zone of proteolytic activity, which corresponded to the band obtained with SDS-PAGE indicating that this could be a single-polypeptide enzyme.
Assuntos
Animais , Aprotinina/farmacologia , Cromatografia em Agarose , Quimotripsina/isolamento & purificação , Sistema Digestório/enzimologia , Eletroforese em Gel de Poliacrilamida , Elettaria/parasitologia , Frutas/parasitologia , Larva , Lepidópteros/enzimologia , Elastase Pancreática/isolamento & purificação , Brotos de Planta/parasitologia , Conformação Proteica , Inibidores de Serina Proteinase/farmacologiaRESUMO
The effect of two insect growth regulators of plant origin viz. plumbagin and azadirachtin and the ecdysteroids 20-hydroxyecdysone, makisterone A and a phytoecdysteroid on DNA synthesis in imaginal wing discs of day 4 final instar Helicoverpa armigera larvae was studied. DNA synthesis increased with increase in time of incubation up to 8 h and decreased later without the addition of moulting hormone. Addition of 20-hydroxyecdysone supported long term acquisition of competence for DNA synthesis in the wing discs. Both DNA synthesis and protein content were drastically reduced in plumbagin and azadirachtin-treated insects. Under in vitro conditions, plumbagin had a more pronounced inhibitory effect than azadirachtin. All the ecdysteroids tested, viz. makisterone A, 20-hydroxyecdysone and the ecdysteroidal fraction from the silver fern Cheilanthes farinosa enhanced DNA synthesis.