With support from the Analytical and Surface Chemistry Program in the Division of Chemistry, and the Arctic and Antarctic Programs in the Office of Polar Programs, a collaborative team involving the groups of Prof. Andrzej Wierzbicki at the University of South Alabama and Prof. Jeffy Madura at Duquesne University is studying structure-function relationships in the mechanism of action of Type I antifreeze proteins (AFPs). The specific aim of this research is to elucidate the importance of the contribution of nonpolar interactions to molecular recognition and binding. The Type I AFPs are small alpha-helical proteins which protect certain species of fish from freezing by a non-colligative mechanism of freezing point depression. This protective mechanism relies on the subtle functional design of these proteins which masterfully utilizes both polar and nonpolar residues to minimize the free energy at the water/ice interfacial region. The collaborators use molecular dynamics simulations to study the various molecular interactions, both hydrophobic and hydrophilic, that influence the recognition and binding of AFPs at water/ice interfaces. The potential of mean force method will be used for direct computation of the Gibbs free energies of Type I AFPs at the water/ice interfaces. The broader molecular mechanism by which AFPs inhibit the growth of ice and interact with phospholipid membranes will be also studied to elucidate how the AFPs protect living organisms from freezing. Based on the computational studies, functional AFP analogues will be designed and experimentally tested to investigate the importance of nonpolar interactions for molecular recognition and binding at water/ice interfaces.
These studies have the potential for impact in diverse fields including agriculture, medicine, aircraft, and oil and gas exploration and refining. They will provide for training and education in multidisciplinary sciences by providing a novel research experience for graduates and undergraduates. They will encourage, motivate, and nurture the next generation of chemists to integrate state-of-the-art computational and experimental methods into their repertoire of research skills and tools. Specifically a minimum of 3 undergraduates will be trained each year in the integration of experimental and computational methods to study interdisciplinary problems in science.
