Amish Patel, Ph.D. Assistant Professor, Department of Chemical and Biomolecular Engineering, University of Pennsylvania

Uncovering the Molecular Basis for Ice Recognition by Thermal Hysteresis Proteins

Abstract

Organisms that survive in frigid conditions have evolved to contain molecules known as thermal hysteresis proteins (THPs). THPs inhibit ice formation and associated cell death by binding to ice nuclei and preventing their growth. However, how THPs are able to perform one of the most challenging recognition tasks in biology; that of distinguishing between two different phases of water (liquid and ice) remains an open question. The answer to this question has important implications on the rational design of materials that can serve as kinetic inhibitors of ice nucleation; such materials are important in a variety of contexts, ranging from increasing the freeze tolerance of crop plants and the preservation of organs for transplant, to the transportation of frozen foods and low-fat ice-cream. We propose to address this question by employing atomistic simulations in conjunction with enhanced sampling methods. We will identify the distinguishing properties of the THP hydration shell water that reflect the icephilicity (affinity for ice) of the underlying protein surface. Further, by characterizing the molecular signatures of icephility over a broad range of temperatures, and for THPs that span a wide range of activities, the proposed work will uncover the molecular underpinnings of ice recognition by these incredible molecules.

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