Enzymatic properties of α- and β-glocusidases extracted from midgut and salivary glands of rice striped stem borer, Chilo suppressalis Walker (Lepidoptera: Pyralidae)

Abstract

The study of digestive enzymes, especially in important pests like Chilo suppressalis Walker (Lepidoptera: Pyralidae), which are a key constraint on rice production in a wide area of the globe and also in Iran, could be a successful procedure in the development of a safe and useful control strategy. Glycosidase are a type of digestive enzymes which have a critical role in the final stages of carbohydrate digestion; they hydrolyze α-D-(1,4)-glucose linkage such as p-nitrophenyl-α-D-glucoside in di and oligosaccharide components. Laboratory reared 4th instar larvae were randomly selected; midgut and salivary gland were removed by dissection under a stereo microscope and glucosidase activities were assayed by Ferreira and Terra's procedures. The activities of αand βglucosidase in the midgut and salivary gland were 0.009, 0.0063, 0.005 and 0.003 µmol/min/mg protein, respectively. The optimal pH and temperature for enzyme activity were determined to be 9 and 45 • C for the glucosidases measured, values which are in agreement with other reports, especially in lepidopteran insects, which give values between 8-12 and 20-50 • C. The enzyme activity increased with the addition of NaCl, MgCl 2 and CaCl 2 and decreased due to the use of different concentrations of KCl, Urea, EDTA, SDS and Urea both in midgut and the salivary glands. Control of pests by using resistant varieties is one of the most important practices that are dependent on inhibitors in plants. Hence, characterization of digestive enzymes, especially the effect of inhibitors on enzyme activity, could be useful, on the one hand for a better understanding of enzyme roles in the nutrition physiology of insects, and on the other hand to reach safe and useful controls of insect pests.

PURIFICATION AND CHARACTERIZATION OF β‐GLUCOSIDASE FROM GREATER WAX MOTH Galleria mellonella L. (LEPIDOPTERA: PYRALIDAE)

“…). Similar temperature optima of β‐glucosidases have been reported from an insect rice striped stem borer (Zibaee et al., ) and from several other organisms (Saha and Bothast, ; Hernandez et al., ; Turan and Zheng, ), but also found lower than for some insect and other sources of β‐glucosidases that show the highest enzymatic activity at around 50°C (Chen and Halkier, ; Pontoh and Low, ; Bernardi et al., ; Li et al., ). Increased catalytic activity at higher temperatures, such as 50°C, is not physiologically meaningful because the activity is lost due to thermal denaturation in a very short incubation time (Li et al., ; Turan and Zheng, ).…”

Rhynchophorus ferrugineus attack affects a group of compounds rather than rearranging Phoenix canariensis metabolic pathways

“…The increases in quinic acid and most sugars, not including glucose, in the 1 st stage-attacked plants compared with healthy plants has been observed in other metabolomics studies aimed at studying plant reactions to stem borers (Zibaee et al 2009;Leiss et al 2009). Thus, they could be linked to a direct plant reaction to the pest activity (Wingler and Roitsch 2008).…”

Short-time dynamics of pH-dependent conformation and substrate binding in the active site of beta-glucosidases: A computational study

“…Experimental determinations of structures for one BG enzyme are obtained typically at one aqueous pH condition that yields the best crystals. 2,19 Therefore, it is challenging to resolve the structural dynamics underlying the pH-dependent BG catalytic action on the substrate, albeit it is well known that enzymatic activity of BGs and related enzymes is influenced significantly by the aqueous pH conditions 2, 16,50 . Furthermore, the direct experimental characterization of the role of interacting water molecules in BG substrate binding is limiting 18 , necessitating complementary insights from molecular modeling.…”

“…13 A large diversity of pH-activity profiles exists for BGs of different origins, and even within the same species. 14 For instance, maximum enzymatic activities of BGs from the anaerobic bacterium Clostridium cellulovorans 2 , the fungi Asperigillus aculeaus 15 and Trichoderma reesi 2 , and the insect Chilo suprressalis 16 occur, respectively, at pH values of 6, 3, 6, and 9. A mechanistic basis for the relationship between enzyme structure and pH-induced effects on BG activity is lacking.…”