STRUCTURAL FEATURES THAT STABILIZE HALOPHILIC MALATE-DEHYDROGENASE FROM AN ARCHAEBACTERIUM
STRUCTURAL FEATURES THAT STABILIZE HALOPHILIC MALATE-DEHYDROGENASE FROM AN ARCHAEBACTERIUM
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DOI：
10.1126/science.267.5202.1344
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发表时间：
1995-03-03
期刊：
影响因子：
56.9
通讯作者：
SUSSMAN, JL
中科院分区：
文献类型：
--
作者：
DYM, O;MEVARECH, M;SUSSMAN, JL
用x射线晶体学测定了古细菌嗜盐苹果酸脱氢酶（hMDH）的高分辨率结构。通过比较hMDH及其非亲盐同系物的三维结构，揭示了可能促进hMDH在高盐浓度下稳定性的结构特征。这些特征包括分布在酶表面的酸性残基多于碱性残基，以及与非嗜盐性酶相比，hMDH中存在更多的盐桥。其他有助于稳定嗜热乳酸脱氢酶和亲热mdh的特征也在hMDH中被观察到——将丙氨酸结合到α螺旋中，并在其氨基末端附近引入带负电荷的氨基酸，这两者都是由于与α螺旋偶极子的正部分相互作用而稳定α螺旋的结果。
The high-resolution structure of halophilic malate dehydrogenase (hMDH) from the archaebacterium Haloarcula marismortui was determined by x-ray crystallography. Comparison of the three-dimensional structures of hMDH and its nonhalophilic congeners reveals structural features that may promote the stability of hMDH at high salt concentrations. These features include an excess of acidic over basic residues distributed on the enzyme surface and more salt bridges present in hMDH compared with its nonhalophilic counterparts. Other features that contribute to the stabilization of thermophilic lactate dehydrogenase and thermophilic MDH-the incorporation of alanine into alpha helices and the introduction of negatively charged amino acids near their amino termini, both of which stabilize the alpha helix as a result of interaction with the positive part of the alpha-helix dipole-also were observed in hMDH.