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Structure and enzyme properties of Zabrotes subfasciatus α‐amylase
Author(s) -
Pelegrini Patrícia B.,
Murad André M.,
GrossideSá Maria F.,
Mello Luciane V.,
Romeiro Luiz A.S.,
Noronha Eliane F.,
Caldas Ruy A.,
Franco Octávio L.
Publication year - 2006
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.20099
Subject(s) - phaseolus , amylase , starch , hydrolysis , enzyme , biology , biochemistry , insect , enzyme assay , food science , carbohydrate , divalent , botany , chemistry , organic chemistry
Digestive α‐amylases play an essential role in insect carbohydrate metabolism. These enzymes belong to an endo‐type group. They catalyse starch hydrolysis, and are involved in energy production. Larvae of Zabrotes subfasciatus , the Mexican bean weevil, are able to infest stored common beans Phaseolus vulgaris , causing severe crop losses in Latin America and Africa. Their α‐amylase (ZSA) is a well‐studied but not completely understood enzyme, having specific characteristics when compared to other insect α‐amylases. This report provides more knowledge about its chemical nature, including a description of its optimum pH (6.0 to 7.0) and temperature (20–30°C). Furthermore, ion effects on ZSA activity were also determined, showing that three divalent ions (Mn 2+ , Ca 2+ , and Ba 2+ ) were able to enhance starch hydrolysis. Fe 2+ appeared to decrease α‐amylase activity by half. ZSA kinetic parameters were also determined and compared to other insect α‐amylases. A three‐dimensional model is proposed in order to indicate probable residues involved in catalysis (Asp 204 , Glu 240 , and Asp 305 ) as well other important residues related to starch binding (His 118 , Ala 206 , Lys 207 , and His 304 ). Arch. Insect Biochem. Physiol. 61:77–86, 2006. © 2006 Wiley‐Liss, Inc.