title: Utilizing avidity to improve antifreeze protein activity: a type III antifreeze protein trimer exhibits increased thermal hysteresis activity.
abstract: Antifreeze proteins (AFPs) are ice growth inhibitors that allow the survival of several species living at temperatures colder than the freezing point of their bodily fluids. AFP activity is commonly defined in terms of thermal hysteresis, which is the difference observed for the solution freezing and melting temperatures. Increasing the thermal hysteresis activity of these proteins, particularly at low concentrations, is of great interest because of their wide range of potential applications. In this study, we have designed and expressed one-, two-, and three-domain antifreeze proteins to improve thermal hysteresis activity through increased binding avidity. The three-domain type III AFP yielded significantly greater activity than the one- and two-domain proteins, reaching a thermal hysteresis of >1.6 °C at a concentration of <1 mM. To elucidate the basis of this increase, the data were fit to a multidomain protein adsorption model based on the classical Langmuir isotherm. Fits of the data to the modified isotherms yield values for the equilibrium binding constants for the adsorption of AFP to ice and indicate that protein surface coverage is proportional to thermal hysteresis activity.
authors.affiliation: Department of Chemical and Biomedical Engineering, Cleveland State University , 2121 Euclid Avenue, Cleveland, Ohio 44115, United States.
authors.forename: Özge
authors.initials: Ö
authors.lastname: Can
authors.forename: Nolan B
authors.initials: NB
authors.lastname: Holland
mesh_terms: D000818:Animals; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000235:genetics; D003080:Cold Temperature; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000737:chemistry / Q000494:pharmacology; D004524:Eels; D008958:Models, Molecular; D011485:Protein Binding; D015202:Protein Engineering / Q000379:methods*; D017510:Protein Folding; D055503:Protein Multimerization / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: D021301:Antifreeze Proteins; D003451:Cryoprotective Agents; D011994:Recombinant Proteins