Título:	Mutants of common bean alpha-amylase inhibitor-2 as an approach to investigate binding specificity to alpha-amylases.
Autoria:	SILVA, M. C. M. da MELLO, L. V. COUTINHO, M. V. RIGDEN, D. J. NESHICH, G. CHRISPEELS, M. J. GROSSI-DE-SÁ, M. F.
Ano de publicação:	2004
Referência:	Pesquisa Agropecuária Brasileira, Brasília, DF, v. 39, n. 3, p. 201-208, mar. 2004.
Conteúdo:	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
Palavras-chave:	Inibidores de a-amilases Especificidade de interação mutagênese sítio-dirigida Modelagem molecular
Tipo do material:	Artigo de periódico
Acesso:	openAccess
Aparece nas coleções:	Artigo em periódico indexado (CNPTIA)