Enzymes and proteins from organisms that grow near and above 100 degrees C.
Enzymes and proteins from organisms that grow near and above 100 degrees C.
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DOI：
10.1146/annurev.mi.47.100193.003211
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发表时间：
1993
影响因子：
10.5
通讯作者：
M. Adams
中科院分区：
文献类型：
--
作者：
M. Adams
10年前发现了可以在100摄氏度以上生长的微生物，现在已知大约有20种不同的属。这些所谓的超嗜热生物是现存生命中最古老的;除了两个属外，所有属都被归类为超嗜热生物。所有这些都与地热加热环境，包括深海热液喷口隔绝。这一组包括一些产甲烷和硫酸盐还原物种，但大多数是严格厌氧异养生物，利用复杂的肽混合物作为能源，碳和氮。只有少数几种是糖分解的。大多数超嗜热菌绝对依赖于元素硫（SO）还原为H2S以实现显著生长，这一特性严重限制了它们在传统发酵系统中的大规模培养。因此，大多数生理和代谢研究都集中在那些也可以在没有S 0的情况下生长的物种上，包括热球菌属，热球菌属和热球菌属，以及热袍菌。发酵途径的代谢肽和碳水化合物的葡萄球菌似乎取决于酶，含有钨，一种元素很少用于生物系统。S 0减少和能量保存的机制仍不清楚。从SO还原性超嗜热菌纯化的酶包括蛋白酶、淀粉分解型酶、氢化酶、氧化还原蛋白、各种铁氧还蛋白连接的氧化还原酶、脱氢酶和DNA聚合酶，其中一些酶在高达140 ℃下仍有活性。然而，完整的氨基酸序列是已知的只有少数这些蛋白质，只有一个超嗜热蛋白的三维结构已被确定。蛋白质和各种生物辅因子和有机中间体在极端温度下稳定的潜在机制现在才开始出现。
Microorganisms that can grow at and above 100 degrees C were discovered a decade ago, and about 20 different genera are now known. These so-called hyperthermophiles are the most ancient of all extant life; all but two genera are classified as Archaea. All have been isolated from geothermal heated environments including deep-sea hydrothermal vents. This group includes some methanogenic and sulfate-reducing species, but the majority are strictly anaerobic heterotrophs that utilize complex peptide mixtures as sources of energy, carbon, and nitrogen. Only a few species are saccharolytic. Most of the hyperthermophiles absolutely depend on the reduction of elemental sulfur (S0) to H2S for significant growth, a property that severely limits their large-scale culture in conventional fermentation systems. Consequently, most physiological and metabolic studies have focused on those that can also grow in the absence of S0, including species of the Archaea, Pyrococcus and Thermococcus, and the bacterium Thermotoga. The fermentative pathways for the metabolism of both peptides and carbohydrates in the Archaea appear to depend upon enzymes that contain tungsten, an element seldom used in biological systems. The mechanisms of S0 reduction and energy conservation remain unclear. Enzymes purified from the S0-reducing hyperthermophiles include proteases, amylolytic-type enzymes, hydrogenases, redox proteins, various ferredoxin-linked oxidoreductases, dehydrogenases, and DNA polymerases, some of which are active up to 140 degrees C. However, complete amino acid sequences are known for only a handful of these proteins, and the three-dimensional structure of only one hyperthermophilic protein has been determined. Potential mechanisms by which proteins and various biological cofactors and organic intermediates are stabilized at extreme temperatures are only now beginning to emerge.