Antifreeze Proteins and Their Practical Utilization in Industry, Medicine, and Agriculture

Abstract

Antifreeze proteins (AFPs) are specific proteins, glycopeptides, and peptides made by different organisms to allow cells to survive in sub-zero conditions. AFPs function by reducing the water's freezing point and avoiding ice crystals' growth in the frozen stage. Their capability in modifying ice growth leads to the stabilization of ice crystals within a given temperature range and the inhibition of ice recrystallization that decreases the drip loss during thawing. This review presents the potential applications of AFPs from different sources and types. AFPs can be found in diverse sources such as fish, yeast, plants, bacteria, and insects. Various sources reveal different α-helices and β-sheets structures. Recently, analysis of AFPs has been conducted through bioinformatics tools to analyze their functions within proper time. AFPs can be used widely in various aspects of application and have significant industrial functions, encompassing the enhancement of foods' freezing and liquefying properties, protection of frost plants, enhancement of ice cream's texture, cryosurgery, and cryopreservation of cells and tissues. In conclusion, these applications and physical properties of AFPs can be further explored to meet other industrial players. Designing the peptide-based AFP can also be done to subsequently improve its function.

Keywords: antifreeze glycopeptide; antifreeze protein; application; ice recrystallization inhibition; psychrophiles; thermal hysteresis.

Figure 1

The natural properties of antifreeze proteins (AFPs) (thermal hysteresis and ice recrystallization inhibition) in various organisms in nature. (a) For freezing inhibition, AFPs can block forming of ice crystals in fish and insects by lowering down the freezing points in body fluids. (b) In plants and nematode, freeze-tolerating is carried out by binding the AFPs to the surface of ice and prevent it from becoming larger ice crystals. (c) AFPs of different microorganisms can adhere to the ice surface, like Marinomonas primoryensis, and inhibit the formation of ice crystals. Adhesion of AFPs to ice can be done from three regions: C terminal, N terminal, and intermediate repeat [10].

Figure 2

Ice recrystallization inhibition function of AFPs [12].

Figure 3

Structural properties of AFPs based on binding to ice crystal planes, which are widely different due to the types and structure of AFPs. Type I AFP has a primary prism shape of the ice plane. Other types can form basal plane, secondary prism, and pyramidal shapes once they interact with ice/water [14].

Figure 4

Antifreeze protein structures. Fish AFPs (a,b,e–g) and two AFPs from insects (c,d) with α-helices, β-strands and coil. (a) Type I AFP from winter flounder, (b) antifreeze glycoprotein (AFGP) with left-handed helix, (c) insect AFP from Spruce budworm, (d) AFP from Tenebrio molitor, (e) Type IV AFP with 4 bundle helices with unknown characteristics, (f,g) non-repetitive AFPs: (f) Type II AFP from sea raven (The protein data bank (PDB) ID: 2AFP) and (g) Type III AFP from ocean pout [41].

Figure 5

Functions of Ixodes scapularis antifreeze glycoprotein (IAFGP) as an anti-virulence element against various microbes, such as the methicillin-resistant Staphylococcus aureus (MRSA) [75].