Antifreeze proteins (AFPs) have been identified in a number of organisms, such as fish, plants, and insects, to allow them to survive at subfreezing temperatures. They are all characterized by their ability to depress the freezing point of the solution without appreciably altering the melting point thereby producing a thermal hysteresis. Insect AFPs are often the most active AFPs (10-100 times more active than type I fish AFPs). The antifreeze activities of many AFPs can be further enhanced in the presence of certain co-solutes (called enhancers). Both low molecular mass chemicals and macromolecules have been identified as enhancers for AFPs and some of the enhancers do play a role in enhancing the antifreeze activity of AFPs physiologically. Some of the enhancers have been reported to bind AFPs specifically. The mechanism of the enhancement effect, however, is still poorly described. The AFP from the beetle Dendroides canadensis (DAFP) and the enhancers have been extensively studied. The binding of enhancers to AFP has been demonstrated as one important mechanism for the enhancement effect of enhancers on the antifreeze activity of AFPs. Is there a common mechanism for the enhancement phenomena in different AFP systems? In this project, we will examine an important beetle AFP system, a mealworm AFP from Tenebrio molitor (TmAFP) and the enhancers. We propose that the enhancement efficiency of the enhancers for TmAFP antifreeze activity depends on the physiochemical properties of the enhancers. We will assess the enhancement efficiency of selected amine derivatives on TmAFP antifreeze activity and correlate their enhancement efficiency with their differing physicochemical properties. We will identify the possible interactions between TmAFP and the enhancers and determine the key amino acids in TmAFP involving in binding to the enhancers. The study of AFPs and enhancers is essential to advance our understanding of the biological system and facilitate the development of highly efficient AFP systems for their practical biomedical applications, such as in preservation of tissues at low temperatures in the lab and in human health as well as other industrial applications, such as in frozen foods and in hydrate inhibition. The proposed research will provide insights into the molecular mechanism of AFP and AFP enhancers and resolve conflicting reports regarding the mechanism of action of AFPs.

Public Health Relevance

The proposed work examines the role of enhancers on the antifreeze properties of antifreeze proteins (AFPs). Antifreeze protection is important in public health (e.g., preservation of tissues at low temperatures and food preservation). The results of the project will advance our understanding of how AFPs and enhancer work, and improve public health by facilitating the biomedical applications of AFPs and enhancers.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Continuance Award (SC3)
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Special Emphasis Panel (ZGM1-MBRS-3 (SC))
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Okita, Richard T
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California State University Los Angeles
Schools of Arts and Sciences
Los Angeles
United States
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Wang, Sen; Wen, Xin; DeVries, Arthur L et al. (2014) Molecular recognition of methyl ?-D-mannopyranoside by antifreeze (glyco)proteins. J Am Chem Soc 136:8973-81
Wang, Sen; Wen, Xin; Golen, James A et al. (2013) Antifreeze protein-induced selective crystallization of a new thermodynamically and kinetically less preferred molecular crystal. Chemistry 19:16104-12
Wen, Xin; Wang, Sen; Amornwittawat, Natapol et al. (2011) Interaction of reduced nicotinamide adenine dinucleotide with an antifreeze protein from Dendroides canadensis: mechanistic implication of antifreeze activity enhancement. J Mol Recognit 24:1025-32
Wang, Sen; Amornwittawat, Natapol; Juwita, Vonny et al. (2009) Arginine, a key residue for the enhancing ability of an antifreeze protein of the beetle Dendroides canadensis. Biochemistry 48:9696-703
Wang, Sen; Amornwittawat, Natapol; Banatlao, Joseph et al. (2009) Hofmeister effects of common monovalent salts on the beetle antifreeze protein activity. J Phys Chem B 113:13891-4