Santana Camilla Camerino, Barbosa Leandro A, Júnior Irinaldo Diniz Basílio, Nascimento Ticiano Gomes do, Dornelas Camila Braga, Grillo Luciano A M
Escola de Enfermagem e Farmácia, Universidade Federal de Alagoas, Maceió, AL 57072-900, Brazil.
Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindu, Divinópolis 35501-296, Brazil.
Insects. 2017 Sep 13;8(3):100. doi: 10.3390/insects8030100.
Lipases have key roles in insect lipid acquisition, storage, and mobilization and are also fundamental to many physiological processes in insects. Lipids are an important component of insect diets, where they are hydrolyzed in the midgut lumen, absorbed, and used for the synthesis of complex lipids. The South American palm weevil is one of the most important pests on commercial palm plantations. However, there are few studies about lipid digestion for this insect. In this work, we have described the biochemical characterization of the lipase activity in the posterior midgut of the palm weevil. Lipase activity was highest between the temperatures of 37 °C and 45 °C and at pH 6.5. Lipase activity was also sensitive to variations in salt and calcium concentrations. Lipases have been described structurally as enzymes with the Ser-His-Asp Catalytic Triad, containing an active serine. The serine protease inhibitor PMSF (phenylmethane sulfonyl fluoride) inhibited the lipases from , demonstrating the importance of a serine residue for this activity. The ability of the lipases to hydrolyze -Nitrophenyl esters with different chain lengths has revealed the activities of a broad range of substrates. The lipase activities of increased in the presence of reduced glutathione (GSH) and dithiothreitol (DTT), while in the presence of oxidized glutathione (GSSG), activities were drastically reduced. To our knowledge, this study has provided the first information about lipase activity in the palm weevil.
脂肪酶在昆虫脂质的获取、储存和动员过程中发挥着关键作用，对昆虫的许多生理过程也至关重要。脂质是昆虫食物的重要组成部分，在中肠腔中被水解、吸收，并用于合成复杂脂质。南美棕榈象甲是商业棕榈种植园最重要的害虫之一。然而，针对这种昆虫的脂质消化研究较少。在这项工作中，我们描述了棕榈象甲中肠后部脂肪酶活性的生化特性。脂肪酶活性在37℃至45℃之间以及pH值为6.5时最高。脂肪酶活性对盐和钙浓度的变化也很敏感。从结构上看，脂肪酶是具有丝氨酸-组氨酸-天冬氨酸催化三联体的酶，含有一个活性丝氨酸。丝氨酸蛋白酶抑制剂苯甲基磺酰氟（PMSF）抑制了棕榈象甲的脂肪酶，证明了丝氨酸残基对该活性的重要性。脂肪酶水解不同链长对硝基苯酯的能力揭示了其对多种底物的活性。在还原型谷胱甘肽（GSH）和二硫苏糖醇（DTT）存在的情况下，棕榈象甲的脂肪酶活性增加，而在氧化型谷胱甘肽（GSSG）存在的情况下，活性则大幅降低。据我们所知，本研究首次提供了有关棕榈象甲脂肪酶活性的信息。
