da Costa Samara G, Bates Paul, Dillon Rod, Genta Fernando Ariel
Laboratory of Insect Biochemistry and Physiology, Oswaldo Cruz Institute, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom.
Front Physiol. 2019 Apr 10;10:248. doi: 10.3389/fphys.2019.00248. eCollection 2019.
is the main vector of and exploits different food sources during development. Adults have a diet rich in sugars, and females also feed on blood. The sugar diet is essential for maintaining longevity, infection, and Leishmaniasis transmission. Carbohydrases, including α-glucosidases, are the main enzymes involved in the digestion of sugars. In this context, we studied the modulation of α-glucosidase activities in different feeding conditions and compartments of females, in order to characterize in detail their roles in the physiology of this insect. All tissues showed activity against MUαGlu and sucrose, with highest activities in the midgut and crop. Activity was 1,000 times higher on sucrose than on MUαGlu. Basal activities were observed in non-fed insects; blood feeding induced activity in the midgut contents, and sugar feeding modulated activity in midgut tissues. α-glucosidase activity changed after female exposure to different sugar concentrations or moieties. α-glucosidases from different tissues showed different biochemical properties, with an optimum pH around 7.0-8.0 and between 0.37 and 4.7 mM, when MUαGlu was used as substrate. Using sucrose as substrate, the optimum pH was around 6.0, and ranges between 11 and 800 mM. Enzymes from the crop and midgut tissues showed inhibition in high substrate concentrations (sucrose), with ranging from 39 to 400 mM, which explains the high values found. Chromatographic profiles confirmed that different α-glucosidases are been produced in in different physiological contexts, with the distinction of at least four α-glucosidases. The results suggest that some of these enzymes are involved in different metabolic processes, like digestion of plant sugars, digestion of blood glycoproteins or glycolipids, and mobilization of energetic storages during starvation.
是……的主要传播媒介，在发育过程中利用不同的食物来源。成虫的饮食富含糖分，雌性还以血液为食。糖饮食对于维持寿命、感染和利什曼病传播至关重要。包括α - 葡萄糖苷酶在内的碳水化合物酶是参与糖消化的主要酶。在此背景下，我们研究了不同取食条件和雌性……不同部位中α - 葡萄糖苷酶活性的调节，以便详细表征它们在这种昆虫生理学中的作用。所有组织对MUαGlu和蔗糖均表现出活性，中肠和嗉囊中活性最高。蔗糖上的活性比MUαGlu高1000倍。未取食的昆虫中观察到基础活性；取食血液诱导中肠内容物中的活性，而取食糖调节中肠组织中的活性。雌性暴露于不同糖浓度或部分后，α - 葡萄糖苷酶活性发生变化。当使用MUαGlu作为底物时，来自不同组织的α - 葡萄糖苷酶表现出不同的生化特性，最适pH约为7.0 - 8.0，Km在0.37至4.7 mM之间。使用蔗糖作为底物时，最适pH约为6.0，Km在11至800 mM之间。嗉囊和中肠组织中的酶在高底物浓度（蔗糖）下表现出抑制作用，Km范围为39至400 mM，这解释了所发现的高Km值。色谱图谱证实，在……不同生理环境中产生了不同的α - 葡萄糖苷酶，至少有四种α - 葡萄糖苷酶有区别。结果表明，其中一些酶参与不同的代谢过程，如植物糖的消化、血液糖蛋白或糖脂的消化以及饥饿期间能量储存的动员。
