Purification and characterization of midgut α-amylase in a predatory bug, Andralus spinidens.
α-Amylases are widespread enzymes that catalyze endohydrolysis of long α-1,4-glucan chains such as starch and glycogen. The highest amylolytic activity was found in 5th instar nymphs and midgut of the predatory bug, Andrallus spinidens F. (Hemiptera: Pentatomidae). The α-amylase was purified following a three-step procedure. The purified α-amylase had a specific activity of 13.46 U/mg protein, recovery of 4.21, purification fold of 13.87, and molecular weight of 21.3 kDa. The enzyme had optimal pH and temperature of 7 and 45°C, respectively. Na+, Mn+, Mg2+, and Zn2+ significantly decreased activity of the purified α-amylase, but some concentrations of K+, Ca2+, and Cu2+ had the opposite effect. EDTA, EGTA, and DTC significantly decreased enzymatic activity, showing the presence of metal ions in the catalytic site of the enzyme. Kinetic parameters of the purified α-amylase showed a Km of 3.71% in starch and 4.96% for glycogen, suggesting that the enzyme had a higher affinity for starch.
Department of Plant Protection, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran ssa1510607@yahoo.com.
Sahar
S
Sorkhabi-Abdolmaleki
Biological Control Department, Iranian Research Institute of Plant Protection, Amol, Iran arash.zibaee@gmx.com.
Arash
A
Zibaee
Biological Control Department, Iranian Research Institute of Plant Protection, Amol, Iran mehranhoda@yahoo.com.
Hassan
H
Hoda
Department of Medical Entomology, Health Sciences Research Center, Faculty of Health, Mazandaran University of Medical Science, Sari, Iran fazelidinan@gmail.com.
Mahmoud
M
Fazeli-Dinan
D000818:Animals; D041981:Gastrointestinal Tract / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D007313:Insecta / Q000201:enzymology*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism*
D019476:Insect Proteins; D000516:alpha-Amylases
amylolytic activity; biochemical property; inhibitor