Aghajari N, Feller G, Gerday C, Haser R
Institut de Biologie et Chimie des Protéines UPR 412, CNRS 7 Passage du Vercors 69367 Lyon cedex 07 France.
Structure. 1998 Dec 15;6(12):1503-16. doi: 10.1016/s0969-2126(98)00149-x.
. Enzymes from psychrophilic (cold-adapted) microorganisms operate at temperatures close to 0 degreesC, where the activity of their mesophilic and thermophilic counterparts is drastically reduced. It has generally been assumed that thermophily is associated with rigid proteins, whereas psychrophilic enzymes have a tendency to be more flexible.
. Insights into the cold adaptation of proteins are gained on the basis of a psychrophilic protein's molecular structure. To this end, we have determined the structure of the recombinant form of a psychrophilic alpha-amylase from Alteromonas haloplanctis at 2.4 A resolution. We have compared this with the structure of the wild-type enzyme, recently solved at 2.0 A resolution, and with available structures of their mesophilic counterparts. These comparative studies have enabled us to identify possible determinants of cold adaptation.
. We propose that an increased resilience of the molecular surface and a less rigid protein core, with less interdomain interactions, are determining factors of the conformational flexibility that allows efficient enzyme catalysis in cold environments.
嗜冷（冷适应）微生物的酶在接近0摄氏度的温度下发挥作用，而它们的嗜温和嗜热同类酶的活性在该温度下会急剧降低。一般认为嗜热性与刚性蛋白质相关，而嗜冷酶往往更具柔韧性。
基于一种嗜冷蛋白质的分子结构，对蛋白质的冷适应有了深入了解。为此，我们已确定了来自嗜盐栖 Alteromonas 菌的一种嗜冷α淀粉酶重组形式的结构，分辨率为2.4埃。我们将此与最近以2.0埃分辨率解析的野生型酶的结构以及它们嗜温同类酶的可用结构进行了比较。这些比较研究使我们能够确定冷适应的可能决定因素。
我们提出，分子表面弹性增加以及蛋白质核心刚性降低且结构域间相互作用减少，是构象灵活性的决定因素，这种灵活性使得酶能够在寒冷环境中高效催化。
