Electron Microscope Unit, University of Cape Town, South Africa.
J Appl Microbiol. 2009 Mar;106(3):703-27. doi: 10.1111/j.1365-2672.2008.03941.x. Epub 2008 Nov 8.
The nitrilases are enzymes that convert nitriles to the corresponding acid and ammonia. They are members of a superfamily, which includes amidases and occur in both prokaryotes and eukaryotes. The superfamily is characterized by having a homodimeric building block with a alpha beta beta alpha-alpha beta beta alpha sandwich fold and an active site containing four positionally conserved residues: cys, glu, glu and lys. Their high chemical specificity and frequent enantioselectivity makes them attractive biocatalysts for the production of fine chemicals and pharmaceutical intermediates. Nitrilases are also used in the treatment of toxic industrial effluent and cyanide remediation. The superfamily enzymes have been visualized as dimers, tetramers, hexamers, octamers, tetradecamers, octadecamers and variable length helices, but all nitrilase oligomers have the same basic dimer interface. Moreover, in the case of the octamers, tetradecamers, octadecamers and the helices, common principles of subunit association apply. While the range of industrially interesting reactions catalysed by this enzyme class continues to increase, research efforts are still hampered by the lack of a high resolution microbial nitrilase structure which can provide insights into their specificity, enantioselectivity and the mechanism of catalysis. This review provides an overview of the current progress in elucidation of structure and function in this enzyme class and emphasizes insights that may lead to further biotechnological applications.
腈水解酶是一种将腈转化为相应酸和氨的酶。它们是一个超家族的成员，包括酰胺酶，存在于原核生物和真核生物中。该超家族的特征是具有同源二聚体构建块，具有αβββα-αββα三明治折叠，并且活性位点包含四个位置保守的残基：半胱氨酸、谷氨酸、谷氨酸和赖氨酸。它们具有很高的化学特异性和频繁的对映选择性，因此成为生产精细化学品和药物中间体的有吸引力的生物催化剂。腈水解酶也用于处理有毒工业废水和氰化物修复。超家族酶已被可视化成二聚体、四聚体、六聚体、八聚体、十四聚体、十八聚体和可变长度螺旋体，但所有的腈水解酶寡聚体都具有相同的基本二聚体界面。此外，在八聚体、十四聚体、十八聚体和螺旋体的情况下，亚基缔合的共同原则适用。虽然该酶类催化的工业上有趣的反应范围继续增加，但由于缺乏高分辨率微生物腈水解酶结构，研究工作仍然受到阻碍，该结构可以提供对其特异性、对映选择性和催化机制的深入了解。本综述概述了在阐明该酶类的结构和功能方面的最新进展，并强调了可能导致进一步生物技术应用的见解。
