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从土曲霉多功能提取物中鉴定共纯化的转化酶和β-葡萄糖苷酶。

Characterization of the co-purified invertase and β-glucosidase of a multifunctional extract from Aspergillus terreus.

机构信息

Instituto de Química de Araraquara, UNESP, Rua Professor Francisco Degni s/n, Quitandinha, Araraquara, SP, 14800-900, Brazil.

出版信息

World J Microbiol Biotechnol. 2014 May;30(5):1501-10. doi: 10.1007/s11274-013-1570-3. Epub 2013 Dec 5.

Abstract

The filamentous fungus Aspergillus terreus secretes both invertase and β-glucosidase when grown under submerged fermentation containing rye flour as the carbon source. The aim of this study was to characterize the co-purified fraction, especially the invertase activity. An invertase and a β-glucosidase were co-purified by two chromatographic steps, and the isolated enzymatic fraction was 139-fold enriched in invertase activity. SDS-PAGE analysis of the co-purified enzymes suggests that the protein fraction with invertase activity was heterodimeric, with subunits of 47 and 27 kDa. Maximal invertase activity, which was determined by response surface methodology, occurred in pH and temperature ranges of 4.0-6.0 and 55-65 °C, respectively. The invertase in co-purified enzymes was stable for 1 h at pH 3.0-10.0 and maintained full activity for up to 1 h at 55 °C when diluted in water. Invertase activity was stimulated by 1 mM concentrations of Mn²⁺ (161 %), Co²⁺ (68 %) and Mg²⁺ (61 %) and was inhibited by Al³⁺, Ag⁺, Fe²⁺ and Fe³⁺. In addition to sucrose, the co-purified enzymes hydrolyzed cellobiose, inulin and raffinose, and the apparent affinities for sucrose and cellobiose were quite similar (K(M) = 22 mM). However, in the presence of Mn²⁺, the apparent affinity and V(max) for sucrose hydrolysis increased approximately 2- and 2.9-fold, respectively, while for cellobiose, a 2.6-fold increase in V(max) was observed, but the apparent affinity decreased 5.5-fold. Thus, it is possible to propose an application of this multifunctional extract containing both invertase and β-glucosidase to degrade plant biomass, thus increasing the concentration of monosaccharides obtained from sucrose and cellobiose.

摘要

在含有黑麦粉作为碳源的浸没发酵中,丝状真菌土曲霉(Aspergillus terreus)分泌的既有转化酶又有β-葡萄糖苷酶。本研究的目的是对共纯化的部分进行特征分析,尤其是转化酶活性。通过两步色谱法共纯化了一种转化酶和一种β-葡萄糖苷酶,分离出的酶级分在转化酶活性方面富集了 139 倍。共纯化酶的 SDS-PAGE 分析表明,具有转化酶活性的蛋白质部分是异源二聚体,亚基大小分别为 47 和 27 kDa。通过响应面法确定的最大转化酶活性出现在 pH 值 4.0-6.0 和温度 55-65°C 的范围内。共纯化酶中的转化酶在 pH 值 3.0-10.0 下稳定 1 小时,在水中稀释时,在 55°C 下保持 1 小时的全部活性。1 mM 浓度的 Mn²⁺(161%)、Co²⁺(68%)和 Mg²⁺(61%)可刺激转化酶活性,而 Al³⁺、Ag⁺、Fe²⁺和 Fe³⁺则抑制转化酶活性。除蔗糖外,共纯化的酶还水解纤维二糖、菊粉和棉子糖,且对蔗糖和纤维二糖的表观亲和力相当(K(M) = 22 mM)。然而,在 Mn²⁺存在的情况下,蔗糖水解的表观亲和力和 V(max)分别约增加了 2-和 2.9 倍,而对于纤维二糖,V(max)增加了 2.6 倍,但表观亲和力降低了 5.5 倍。因此,有可能提出一种应用,即用这种同时含有转化酶和β-葡萄糖苷酶的多功能提取物来降解植物生物质,从而提高从蔗糖和纤维二糖获得的单糖浓度。

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