Structure and enzyme properties of Zabrotes subfasciatus α-amylase

• Published in: Archives of insect biochemistry and physiology Vol. 61; no. 2; pp. 77 - 86
• Main Authors: Pelegrini, Patrícia B., Murad, André M., Grossi-de-Sá, Maria F., Mello, Luciane V., Romeiro, Luiz A.S., Noronha, Eliane F., Caldas, Ruy A., Franco, Octávio L.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.02.2006
• Subjects: alpha-Amylases - chemistry; alpha-Amylases - metabolism; Amino Acid Sequence; Animals; bean bruchid; Coleoptera - enzymology; enzyme activity; Enzyme Stability; Gene Expression Regulation, Enzymologic; Hydrogen-Ion Concentration; molecular modelling; Molecular Sequence Data; Protein Conformation; Sequence Homology, Amino Acid; Temperature; Zabrotes subfasciatus; α-amylase
• ISSN: 0739-4462; 1520-6327
• DOI: 10.1002/arch.20099

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 (Mn2+, Ca2+, and Ba2+) were able to enhance starch hydrolysis. Fe2+ 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 (Asp204, Glu240, and Asp305) as well other important residues related to starch binding (His118, Ala206, Lys207, and His304). Arch. Insect Biochem. Physiol. 61:77–86, 2006. © 2006 Wiley‐Liss, Inc.