UCIBIO@REQUIMTE, BioSIM, Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal.
Molecules. 2019 Jul 4;24(13):2462. doi: 10.3390/molecules24132462.
Nature has tailored a wide range of metalloenzymes that play a vast array of functions in all living organisms and from which their survival and evolution depends on. These enzymes catalyze some of the most important biological processes in nature, such as photosynthesis, respiration, water oxidation, molecular oxygen reduction, and nitrogen fixation. They are also among the most proficient catalysts in terms of their activity, selectivity, and ability to operate at mild conditions of temperature, pH, and pressure. In the absence of these enzymes, these reactions would proceed very slowly, if at all, suggesting that these enzymes made the way for the emergence of life as we know today. In this review, the structure and catalytic mechanism of a selection of diverse metalloenzymes that are involved in the production of highly reactive and unstable species, such as hydroxide anions, hydrides, radical species, and superoxide molecules are analyzed. The formation of such reaction intermediates is very difficult to occur under biological conditions and only a rationalized selection of a particular metal ion, coordinated to a very specific group of ligands, and immersed in specific proteins allows these reactions to proceed. Interestingly, different metal coordination spheres can be used to produce the same reactive and unstable species, although through a different chemistry. A selection of hand-picked examples of different metalloenzymes illustrating this diversity is provided and the participation of different metal ions in similar reactions (but involving different mechanism) is discussed.
自然界已经设计了各种各样的金属酶，这些酶在所有生物中发挥着广泛的功能，其生存和进化都依赖于这些酶。这些酶催化了自然界中一些最重要的生物过程，如光合作用、呼吸作用、水氧化、分子氧还原和氮固定。就其活性、选择性和在温和的温度、pH 值和压力条件下工作的能力而言，它们也是最有效的催化剂之一。如果没有这些酶，这些反应的速度会非常缓慢，如果有的话，这表明这些酶为我们今天所知道的生命的出现铺平了道路。在这篇综述中，分析了一系列参与生产高反应性和不稳定物质（如氢氧根阴离子、氢化物、自由基和超氧分子）的不同金属酶的结构和催化机制。在生物条件下，形成这样的反应中间体是非常困难的，只有对特定的金属离子进行合理化选择，与非常特定的配体基团配位，并沉浸在特定的蛋白质中，才能使这些反应进行。有趣的是，尽管化学性质不同，但不同的金属配位球可以用来产生相同的反应性和不稳定物质。提供了一系列精选的不同金属酶的例子来说明这种多样性，并讨论了不同金属离子在类似反应（但涉及不同机制）中的参与。
