In situ observation of antifreeze glycoprotein kinetics at the ice interface reveals a two-step reversible adsorption mechanism
In situ observation of antifreeze glycoprotein kinetics at the ice interface reveals a two-step reversible adsorption mechanism
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DOI：
10.1021/cg800269w
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发表时间：
2008-10-01
影响因子：
3.8
通讯作者：
Furukawa, Yoshinori
中科院分区：
文献类型：
--
作者：
Zepeda, Salvador;Yokoyama, Etsuro;Furukawa, Yoshinori
抗冻糖蛋白（AFGPs）是生活在冰点以下环境中的鱼类生存的必要工具[Yeh，Y.;菲尼河E.抗冻蛋白的结构和功能机制。1996，96（2），601-617]。尽管科学家们一致认为这些蛋白质通过表面吸附机制阻止冰晶生长，但相互作用的确切性质仍然是一个悬而未决的问题。在这里，我们研究的吸附动力学AFGPs在溶液中冰晶生长过程中，使用共聚焦荧光显微镜内和下面的冻融温度滞后区。冰表面的AFGP动力学揭示了两步抑制过程：（i）不完全吸附或弱相互作用，改变表面（ii）更强的相互作用，以实现停止生长所需的完全吸附。生长从粗糙界面变为多面界面，并且生长在过冷度小于0.05 ℃时停止。然而，生长恢复，并且蛋白质解吸，返回溶液相，并且不像先前提出的那样并入冰晶中。我们的研究结果是相反的吉布斯-汤姆森模型所描述的AFGP机制。我们认为，另一种解释必须包括一个溶剂化的蛋白质与溶剂化的冰表面相互作用。虽然热力学大大改变了界面区域，防冻作用是一个纯粹的动力学现象。
Antifreeze glycoproteins (AFGPs) are a necessary tool for the survival of fish that live in subfreezing environments [Yeh, Y.; Feeney, R. E. Antifreeze proteins-Structures and mechanisms of function. Chem. Rev. 1996, 96 (2), 601-617]. Although scientists agree that these proteins arrest ice crystal growth by a surface adsorption mechanism, the exact nature of the interaction remains an open question. Here, we study the adsorption kinetics of AFGPs during solution ice crystal growth using confocal fluorescence microscopy within and just below the freezing-melting temperature hysteresis region. The AFGP kinetics at the ice surface reveal a two-step inhibition process: (i) incomplete adsorption or a weak interaction that modifies the surface for (ii) a stronger interaction to achieve the complete adsorption necessary to halt growth. The growth is modified from a rough interface to a faceted one, and growth is halted at supercoolings less than 0.05 degrees C. However, growth resumes, and the proteins desorb, return to the solution phase, and are not incorporated into the ice crystal as previously proposed. Our findings are contrary to an AFGP mechanism described by the Gibbs-Thomson model. We argue that an alternative explanation must include a solvated protein interacting with a solvated ice surface. While thermodynamics considerably alter the interfacial region, antifreeze action is a purely kinetic phenomenon.