Resolution and partial characterization of proteinases and α-amylases from midguts of larvae of the bruchid beetle Callosobruchus maculatus (F.)

Abstract

1. 1. Three proteinases and four α-amylases wre identified in Callosobruchus maculatus larvae. 2. 2. All proteinases have the same Mr (25,000) and optimum pH between 5.5 and 6.0 and are inhibited by iodoacetic acid, iodoacetamide, pCMB, TLCK, TPCK and E-64. Protein inhibitors of cysteine proteinases isolated from Vigna unguiculata seeds and from chicken egg white also inhibited all three proteinases. 3. 3. The four α-amylases have optimum pH between 5.2 and 6.0 and mol. wt of 56,000, 45,000, 36,000 and 33,000. None of them are inhibited by an α-amylase inhibitor from Phaseolus vulgaris seeds. An α-amylase inhibitor from wheat inhibited the amylases of Mr 45,000, 36,000 and 33,000, but failed to inhibit the α-amylase of Mr 56,000. 4. 4. The possible role of proteinase and α-amylase inhibitors in proteing V. unguiculata against attack by C. maculatus is discussed. © 1989.