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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >Comparison of the molten globule states of thermophilic and mesophilic alpha-amylases
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Comparison of the molten globule states of thermophilic and mesophilic alpha-amylases

机译：嗜热和中温α-淀粉酶的熔融小球状态比较

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In recent years great interest has been generated in the process of protein folding, and the formation of intermediates during the folding process has been proven with new experimental strategies. In the present work, we have examined the molten globule state of Bacillus licheniformis alpha-amylase (BLA) by intrinsic fluorescence and circular dichroism, spectra, 1-anilino naphthalene-8-sulfonate (ANS) binding and proteolytic digestion by pepsin, for comparison to its mesophilic counterpart, Bacillus amyloliquefaciens a-amylase (BAA). At pH 4.0, both enzymes acquire partially folded state which show characteristics of molten globule state. They unfold in such a way that their hydrophobic surfaces are exposed to a greater extent compared to the native forms. Chemical denaturation studies by guanidine hydrochloride and proteolytic digestion with pepsin show that molten globule state of BLA is more stable than from BAA. Results from gel filtration indicate that BAA has the same compactness at pH 4.0 and 7.5. However, molten globule state of BLA is less compact than its native state. The effects of polyols such as trehalose, sorbitol and glycerol on refolding of enzymes from molten globule to native state were also studied. These polyols are effective on refolding of mesophilic alpha-amylase but only slightly effect on BLA refolding. In addition, the folding pathway and stability of intermediate state of the thermophilic and the mesophilic a-amylases are discussed. (c) 2006 Elsevier B.V. All rights reserved.
机译：近年来，人们对蛋白质折叠过程产生了极大的兴趣，并且在折叠过程中中间体的形成已被新的实验策略证明。在本工作中，我们通过固有荧光和圆二色性，光谱，1-苯胺基萘-8-磺酸盐（ANS）结合和胃蛋白酶的蛋白水解消化，研究了地衣芽孢杆菌α-淀粉酶（BLA）的熔融球状状态，以便进行比较与其嗜温芽孢杆菌淀粉淀粉杆菌α-淀粉酶（BAA）相对应。在pH 4.0下，两种酶均获得部分折叠状态，这显示了熔融球状状态的特征。它们以与天然形式相比更大程度暴露于疏水表面的方式展开。盐酸胍的化学变性研究和胃蛋白酶的蛋白水解消化表明，BLA的熔融球状状态比BAA稳定。凝胶过滤的结果表明BAA在pH 4.0和7.5下具有相同的致密性。但是，BLA的熔融球状状态不如其天然状态致密。还研究了海藻糖，山梨糖醇和甘油等多元醇对酶从熔融小球向天然状态重折叠的影响。这些多元醇对嗜温α-淀粉酶的复性有效，但对BLA复性仅轻微影响。此外，还讨论了嗜热和嗜温α-淀粉酶的折叠途径和中间状态的稳定性。 （c）2006 Elsevier B.V.保留所有权利。

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