120th General Meeting of the KCS

Type Poster Presentation
Area Life Chemistry
Room No. Exhibition Hall 2+3
Time 10월 19일 (목요일) 11:00~12:30
Code BIO.P-282
Subject Thermal hysteresis activities of active and inactive isoforms of a type III antifreeze protein from Notched-fin eelpout, Zoarces elongatus Kner
Authors Yeo-Jin Seo, Joon-Hwa Lee*, Ae-Ree Lee, Seo-Ree Choi
Department of Chemistry, Gyeongsang National University, Korea
Abstract Antifreeze proteins (AFPs) or ice structuring proteins (ISPs) refer to a class of polypeptides produced by certain vertebrates, plants, fungi and bacteria that permit their survival in subzero environments. Type III antifreeze protein (AFP) is produced by several species of marine fishes (eelpouts) that inhabit ice-laden waters. The Japanese notched-fin eelpout, Zoarces elongates Kner, produces 13 different AFPIII isoforms (denoted nfeAFP), which have been divided into six SP (nfeAFP1–6) and seven QAE (nfeAFP7–13) isoforms, and the latter was further divided into QAE1 (nfeAFP7–10) and QAE2 (nfeAFP11–13) isoforms. AFPs create a difference between the melting point and freezing point known as thermal hysteresis. The addition of AFPs at the interface between solid ice and liquid water inhibits the thermodynamically favored growth of the ice crystal. Ice growth is kinetically inhibited by the AFPs covering the water-accessible surfaces of ice. Thermal hysteresis is easily measured in the lab with a nanolitre osmometer. Organisms differ in their values of thermal hysteresis. QAE1 isoforms are fully active variants exhibiting both TH and ice-shaping activities but SP- and QAE2-isoforms is defective activity variants. In this study, we have performed thermal hysteresis activity analyses of six kinds of type III AFPs from Zoarces elongatus Kner, nfeAFP8 (QAE1), nfeAFP11 (QAE1), nfeAFP6 (SP), nfeAFP8_tri (Q9V/ L19V/ V20G), nfeAFP11_tri (V9Q/ V19L/ G20V) and nfeAFP6_tri (P19L/ A20V/ G42S). Our results provide insight into the molecular basis of ice-binding and antifreezing activities of type III AFP isoforms.
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