Significant differences in the activities of α-amylases in the absence and presence of polyethylene glycol assayed on eight starches solubilized by two methods
Significant differences in the activities of α-amylases in the absence and presence of polyethylene glycol assayed on eight starches solubilized by two methods
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DOI：
10.1016/j.carres.2006.05.009
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发表时间：
2006-09-04
影响因子：
3.1
通讯作者：
Robyt, John F.
中科院分区：
文献类型：
--
作者：
Mukerjea, Rupendra;Slocum, Giles;Robyt, John F.
淀粉是太阳能量的一种备用化学来源，在植物中发现的一种不溶于水的颗粒，其化学和物理性质因来源而异。颗粒可通过在水中加热或用各种试剂(如1M氢氧化钠)处理而溶解。α-淀粉酶是一种分布广泛的酶，能将淀粉水解成低分子量的麦芽糊精。我们最近发现，单一的α-淀粉酶在两种不同的淀粉上的活性有显著的不同。然后，我们用八种不同的淀粉，分别用121℃高压灭菌和20℃下1M氢氧化钠溶解两种方法，测定了淀粉液化芽孢杆菌和猪胰腺α-淀粉酶的活性。以前，人们发现聚乙二醇能稳定和激活这两种酶的活性，使用一种可溶的直链淀粉作为底物。在酶的基础上加入聚乙二醇组分后，8种淀粉的酶活显著提高，但活性仍有较大差异。与淀粉的不同活性被假设为不同淀粉在溶解时部分保留的二级和三级结构的数量的差异；添加聚乙二醇的活性被假设为从一系列活性较低的形式形成高活性物种。(C)2006爱思唯尔有限公司。保留所有权利。
Starch is a reserve chemical source of the energy of the sun found in plants as a water-insoluble granule that differs in their chemical and physical properties, depending on the source. The granules can be solubilized by heating in water or by treatment with various reagents, such as 1 M NaOH. alpha-Amylases are widely distributed enzymes that initiate the hydrolysis of starch into low molecular weight maltodextrins. We recently found that the activities of a single alpha-amylase on two different starches were significantly different. We then determined the activities of Bacillus amyloliquefaciens and porcine pancreas alpha-amylases, using eight different starches, solubilized by two methods: autoclaving at 121 degrees C and 1 M NaOH at 20 degrees C. There were significant differences in the activities of both of the amylases on all eight of the starches. Previously, it had been found that polyethylene glycol (PEG) stabilized and activated the activities of both enzymes, using a soluble amylose as the substrate. Addition of PEG to the enzymes greatly increased the activities on the eight starches, but the activities still differed significantly. The different activities with the starches were hypothesized as differences in the amounts of secondary and tertiary structures that are partially retained when the different starches are solubilized; the activities on addition of PEG is hypothesized as the formation of highly active species from a series of less active forms. (c) 2006 Elsevier Ltd. All rights reserved.