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首页> 外文期刊>African Journal of Biotechnology >Specific aminopeptidases of indigenous Lactobacillus brevis and Lactobacillus plantarum
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Specific aminopeptidases of indigenous Lactobacillus brevis and Lactobacillus plantarum

机译：本地短乳杆菌和植物乳杆菌的特定氨基肽酶

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Lactic acid bacteria play an important role in milk coagulation and cheese ripening. To select strains showing interesting industrial features, two indigenous lactobacilli (Lactobacillus brevis and Lactobacillus plantarum) were studied for aminopeptidase activity. Cell and cells free extract were tested for leucyl aminopeptidase activity on the chromogenic leucyl-p-nitroanilide substrate. Intracellu-lar and membrane enzymes were solubilized with glycine /lyzozyme treatment then purified by ammonium sulphate precipitation followed by Sephadex G100 and diethylaminoethyl (DEAE) ions exchange chromatography’s separation. The molecular weight of denatured proteins was estimated on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). Effects of several parameters, pH, temperature, some ions and inhibitors on purified enzyme activity were studied. Cellular amino-peptidase activity was higher for CHTD 27 strain than BH14 strain. No aminopeptidase activity was noted in the cell free extract. The results of chromatography sephadex G100 combined to those of electrophoresis allowed suggesting a dimer structure for the native enzyme. The Lb CHTD27 purified enzyme showed maximal activity at pH 6.6 and at 40°C. This enzyme was partially inhibited by ethylenediamine acetic acid (EDTA) and Cu2+ ions but increased by Na2+ and Co2+ ions. The aminopeptidase extracted from Lb BH14 was inhibited by EDTA and phenylmethanesulfonylfluoride or phenylmethylsulfonyl fluoride (PMSF), its maximal activity was observed at pH 7.5 and 40°C. In addition to other characteristics as proteolysis and autolysis, in this paper we showed that both studied strains were also able to degrade peptide with specific peptidases which are important characters in cheese manufacturing.
机译：乳酸菌在牛奶凝结和奶酪成熟中起重要作用。为了选择表现出有趣的工业特征的菌株，研究了两种本地乳酸杆菌（短乳杆菌和植物乳杆菌）的氨肽酶活性。测试无细胞和无细胞提取物在发色的亮氨酰-对硝基苯胺底物上的亮氨酰氨肽酶活性。用甘氨酸/溶菌酶处理溶解细胞内和膜上的酶，然后用硫酸铵沉淀法纯化，然后用Sephadex G100和二乙氨基乙基（DEAE）离子交换色谱分离。在十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS PAGE）上估计变性蛋白质的分子量。研究了几个参数，pH，温度，一些离子和抑制剂对纯化酶活性的影响。 CHTD 27菌株的细胞氨基肽酶活性高于BH14菌株。无细胞提取物中未观察到氨肽酶活性。将sephadex G100色谱分离的结果与电泳结果相结合，可以推测天然酶的二聚体结构。 Lb CHTD27纯化的酶在pH 6.6和40°C下显示最大活性。该酶被乙二胺乙酸（EDTA）和Cu2 +离子部分抑制，但被Na2 +和Co2 +离子增强。 EDTA和苯甲磺酰氟或苯甲基磺酰氟（PMSF）抑制了从Lb BH14提取的氨基肽酶，在pH 7.5和40°C时观察到其最大活性。除了蛋白水解和自溶的其他特征外，在本文中，我们还表明，这两个研究菌株还能够降解具有特定肽酶的肽，这是奶酪生产中的重要特征。

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