Endoproteases from the midgut of larval Spodoptera littoralis include a chymotrypsin-like enzyme with an extended binding site

摘要: Abstract Endoproteases from the lumen of midgut larvae Spodoptera littoralis were characterised with respect to their substrate specificity and pH optimum. Alkaline serine protease activities corresponding trypsin chymotrypsin detected. Cysteine, aspartic or metalloprotease not found, nor was activity associated microbes. Chymotrypsin hydrolysed SA 2 PPpNA, PLpNA, BTEE, 3 pNA casein, but BTpNA, ALpNA SPpNA, indicating an extended binding site. It effectively inhibited by chymostatin, PMSF, antipain, SBTI, BBTI, LBTI, CEOI TEW, unaffected TPCK. Trypsin BApNA, TGPLpNA, TAME BAEE. TLCK, benzamidine, leupeptin, CEOI, aprotinin, pCMPS E-64. Chymostatin, antipain only three inhibitors which effective against both endopeptidases. have a molecular weight 24,000 19,000, respectively, as determined gel filtration. The optimal for enzymes 10.0 using p-nitroanilide substrates, lower esterase substrates (between 8.0 9.5) higher casein hydrolysis (pH 11.0).