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Title: | Mutants of common bean alpha-amylase inhibitor-2 as an approach to investigate binding specificity to alpha-amylases. |
Authors: | SILVA, M. C. M. da![]() ![]() MELLO, L. V. ![]() ![]() COUTINHO, M. V. ![]() ![]() RIGDEN, D. J. ![]() ![]() NESHICH, G. ![]() ![]() CHRISPEELS, M. J. ![]() ![]() GROSSI-DE-SÁ, M. F. ![]() ![]() |
Date Issued: | 2004 |
Citation: | Pesquisa Agropecuária Brasileira, Brasília, DF, v. 39, n. 3, p. 201-208, mar. 2004. |
Description: | Despite the presence of a family of defense proteins, Phaseolus vulgaris can be attacked by bruchid insects resulting in serious damage to stored grains. The two distinct active forms of a-amylase inhibitors, a-AI1 and a-AI2, in P. vulgaris show different specificity toward a-amylases. Zabrotes subfasciatus a-amylase is inhibited by a-AI2 but not by a-AI1. In contrast, porcine a-amylase is inhibited by a-AI1 but not by a-AI2. The objective of this work was to understand the molecular basis of the specificity of two inhibitors in P. vulgaris (a-AI1 and a-AI2) in relation to a-amylases. Mutants of a-AI2 were made and expressed in tobacco plants. The results showed that all the a-AI2 mutant inhibitors lost their activity against the insect a-amylases but none exhibited activity toward the mammalian a-amylase. The replacement of His33 of a-AI2 with the a-AI1-like sequence Ser-Tyr-Asn abolished inhibition of Z. subfasciatus a-amylase. From structural modeling, the conclusion is that the size and complexity of the amylase-inhibitor interface explain why mutation of the N-terminal loop and resultant abolition of Z. subfasciatus a-amylase inhibition are not accompanied by gain of inhibitory activity against porcine a-amylase. |
Thesagro: | Phaseolus Vulgaris |
Keywords: | Inibidores de a-amilases Especificidade de interação mutagênese sítio-dirigida Modelagem molecular |
Type of Material: | Artigo de periódico |
Access: | openAccess |
Appears in Collections: | Artigo em periódico indexado (CNPTIA)![]() ![]() |
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v39n03a01.pdf | 125,26 kB | Adobe PDF | ![]() View/Open |