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Structural insight into substrate specificity of human intestinal maltase-glucoamylase
Protein & Cell ; (12): 827-836, 2011.
Artículo en Inglés | WPRIM | ID: wpr-757034
ABSTRACT
Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. In this study, we report crystal structures of MGAM-C alone at a resolution of 3.1 Å, and in complex with its inhibitor acarbose at a resolution of 2.9 Å. Structural studies, combined with biochemical analysis, revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites (+ 2 and + 3 subsites), accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N. Moreover, we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides. These results provide important information for understanding the substrate specificity of alpha-glucosidases during the process of terminal starch digestion, and for designing more efficient drugs to control type 2 diabetes or obesity.
Asunto(s)
Texto completo: Disponible Índice: WPRIM (Pacífico Occidental) Asunto principal: Oligosacáridos / Pichia / Unión Proteica / Especificidad por Sustrato / Propiedades de Superficie / Proteínas Recombinantes / Datos de Secuencia Molecular / Cinética / Química / Mutagénesis Sitio-Dirigida Límite: Humanos Idioma: Inglés Revista: Protein & Cell Año: 2011 Tipo del documento: Artículo

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Texto completo: Disponible Índice: WPRIM (Pacífico Occidental) Asunto principal: Oligosacáridos / Pichia / Unión Proteica / Especificidad por Sustrato / Propiedades de Superficie / Proteínas Recombinantes / Datos de Secuencia Molecular / Cinética / Química / Mutagénesis Sitio-Dirigida Límite: Humanos Idioma: Inglés Revista: Protein & Cell Año: 2011 Tipo del documento: Artículo