De Simone G, Menchise V, Manco G, Mandrich L, Sorrentino N, Lang D, Rossi M, Pedone C
Centro di Studio di Biocristallografia- CNR, University of Naples "Federico II", via Mezzocannone 6/8, Naples, 80134, Italy.
J Mol Biol. 2001 Nov 30;314(3):507-18. doi: 10.1006/jmbi.2001.5152.
The crystal structure of AFEST, a novel hyper-thermophilic carboxylesterase from the archaeon Archaeoglobus fulgidus, complexed with a sulphonyl derivative, has been determined and refined to 2.2 A resolution. This enzyme, which has recently been classified as a member of the hormone- sensitive-lipase (H) group of the esterase/lipase superfamily, presents a canonical alpha/beta hydrolase core, shielded on the C-terminal side by a cap region composed of five alpha-helices. It contains the catalytic triad Ser160, His285 and Asp255, whereby the nucleophile is covalently modified and the oxyanion hole formed by Gly88, Gly89 and Ala161. A structural comparison of AFEST with its mesophilic and thermophilic homologues, Brefeldin A esterase from Bacillus subtilis (BFAE) and EST2 from Alicyclobacillus acidocaldarius, reveals an increase in the number of intramolecular ion pairs and secondary structure content, as well as a significant reduction in loop extensions and ratio of hydrophobic to charged surface area. The variety of structural differences suggests possible strategies for thermostabilization of lipases and esterases with potential industrial applications.
已确定并精修了来自嗜热栖热放线菌的一种新型超嗜热羧酸酯酶AFEST与一种磺酰基衍生物结合的晶体结构，分辨率达到2.2埃。这种酶最近被归类为酯酶/脂肪酶超家族中激素敏感脂肪酶（H）组的成员，具有典型的α/β水解酶核心，在C端一侧被由五个α螺旋组成的帽状区域所屏蔽。它包含催化三联体Ser160、His285和Asp255，亲核试剂在此被共价修饰，由Gly88、Gly89和Ala161形成氧阴离子洞。对AFEST与其嗜温和嗜热同源物——来自枯草芽孢杆菌的布雷菲德菌素A酯酶（BFAE）和来自嗜酸 Alicyclobacillus acidocaldarius的EST2进行结构比较，发现分子内离子对数量和二级结构含量增加，以及环延伸和疏水与带电表面积之比显著降低。各种结构差异表明了在具有潜在工业应用的脂肪酶和酯酶热稳定化方面可能的策略。
