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| Author(s): |
Fernando Ariel Genta
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2004-04-14 |
| Examining board members: |
Clélia Ferreira;
Maria Júlia Manso Alves;
Pedro Soares de Araujo;
João Atílio Jorge;
Ivarne Luis dos Santos Tersariol
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| Advisor: | Clélia Ferreira |
| Abstract | |
P. americana salivary glands and T. molitor midgut epithelium actively secrete laminarinases into the midgut. The major laminarinases from P. americana (LIQ1, 42kDa and LAM_P, 45kDa), A. flavolineata (LAM_A, 45kDa) and T molitor (LAM_T, 50kDa) were purified until homogeneity. These enzymes have different specificities, action patterns and activesite catalytic groups, and correspond to E.C.s 3.2.1.6 - endo-β-1,3(4)-glucanase (LIQ1), 3.2.1.39 - endo-β-1,3-glucanase (LAM_P) or 3.2.1.58 -exo-β-1,3-glucanase (LAM_A and LAM_T). Their physiological role is fungai and cereal β-glucan digestion. LAM_P and LAM_A are inhibited by excess substrate (non-productive enzyme-substrate complexes). LIQ1, LAM_P and LAMA have different multiple attack degrees and produce different oligosaccharides. LAM_A has a second substrate binding site, probably involved with processivity. T. molitor digestive chitinase is different from other insect chitinases. A. flavolineata and T. molitor can hydrolyse cristalline cellulose efficiently. The three studied insects have cellulose or pachyman-binding proteins with low molecular weights. Hexapoda ancestors probably had digestive β-1,3 and β-1,3(4)-glucanases and a detritivore habit. (AU) | |