Anchored clathrate waters bind antifreeze proteins to ice
Anchored clathrate waters bind antifreeze proteins to ice
复制标题
DOI：
10.1073/pnas.1100429108
复制
发表时间：
2011-05-03
影响因子：
11.1
通讯作者：
Davies, Peter L.
中科院分区：
文献类型：
--
作者：
Garnham, Christopher P.;Campbell, Robert L.;Davies, Peter L.
抗冻蛋白（AFPs）与冰不可逆结合的机制尚未得到解决。AFP的冰结合位点相对疏水，但也含有许多潜在的氢键供体/受体。氢键和疏水效应对冰结合的影响程度已经争论了30多年。在这里，我们通过解析南极细菌AFP的第一个晶体结构阐明了冰的结合机制。这个34 kda结构域是迄今为止确定的最大的AFP结构，折叠成Ca2+结合的平行β -螺旋，具有广泛的冰状表水阵列，通过氢键直接锚定在多肽主链和相邻侧链上。这些结合水与冰的主棱镜和基面形成了极好的三维匹配，并有效地提供了AFP：冰相互作用的广泛的x射线晶体学图像。这张无遮挡的图片显示了AFP吸附到冰上的疏水效应和氢键的作用。我们将这种结合模式称为AFP作用的“锚定包合物”机制。
The mechanism by which antifreeze proteins (AFPs) irreversibly bind to ice has not yet been resolved. The ice-binding site of an AFP is relatively hydrophobic, but also contains many potential hydrogen bond donors/acceptors. The extent to which hydrogen bonding and the hydrophobic effect contribute to ice binding has been debated for over 30 years. Here we have elucidated the ice-binding mechanism through solving the first crystal structure of an Antarctic bacterial AFP. This 34-kDa domain, the largest AFP structure determined to date, folds as a Ca2+-bound parallel beta-helix with an extensive array of ice-like surface waters that are anchored via hydrogen bonds directly to the polypeptide backbone and adjacent side chains. These bound waters make an excellent three-dimensional match to both the primary prism and basal planes of ice and in effect provide an extensive X-ray crystallographic picture of the AFP: ice interaction. This unobstructed view, free from crystal-packing artefacts, shows the contributions of both the hydrophobic effect and hydrogen bonding during AFP adsorption to ice. We term this mode of binding the "anchored clathrate" mechanism of AFP action.