Structural diversity of marine anti-freezing proteins, properties and potential applications: a review

Abstract

Cold-adapted organisms, such as fishes, insects, plants and bacteria produce a group of proteins known as antifreeze proteins (AFPs). The specific functions of AFPs, including thermal hysteresis (TH), ice recrystallization inhibition (IRI), dynamic ice shaping (DIS) and interaction with membranes, attracted significant interest for their incorporation into commercial products. AFPs represent their effects by lowering the water freezing point as well as preventing the growth of ice crystals and recrystallization during frozen storage. The potential of AFPs to modify ice growth results in ice crystal stabilizing over a defined temperature range and inhibiting ice recrystallization, which could minimize drip loss during thawing, improve the quality and increase the shelf-life of frozen products. Most cryopreservation studies using marine-derived AFPs have shown that the addition of AFPs can increase post-thaw viability. Nevertheless, the reduced availability of bulk proteins and the need of biotechnological techniques for industrial production, limit the possible usage in foods. Despite all these drawbacks, relatively small concentrations are enough to show activity, which suggests AFPs as potential food additives in the future. The present work aims to review the results of numerous investigations on marine-derived AFPs and discuss their structure, function, physicochemical properties, purification and potential applications.

Keywords: Function; Ice recrystallization inhibition (IRI); Marine antifreeze proteins; Potential applications; Thermal hysteresis (TH).

Fig. 1

AFPs structures. Representative structures are depicted on a scale for the five types of fish AFP with α helices in red, β strands in green and coil in cyan. a AFP type I from winter flounder (1WFA). b AFP type II from sea raven (2AFP). c AFP type III from ocean pout (1MSI). d Type IV AFP designed as a helix bundle; the question mark showed uncertainty about its repetitive character. e AFGP described as an expanded left-handed helix with disaccharides (Yeh and Feeney 1996). Structures have been developed using Molscript (Kraulis 1991)

Fig. 2

IBP Structure of a Fragilariopsis cylindrus IBP (fcIBP) (Kondo et al. 2018); b cn-AFP obtained using the modeller program (Gwak et al. 2014)

Fig. 3

IBP X-ray crystal structures. a Flavobacterium frigoris PS1 (FfIBP) (Do et al. 2014); b Marinomonas primoryensis (MpAFP) (Garnham et al. 2008)

Fig. 4

Structures of IBP. a LeIBP isolated from psychrophilic yeast Glaciozyma sp. AY30 (Kim et al. 2014); b Typhula ishikariensis (TisIBP6) (Kondo et al. 2012)

Fig. 5

Ice-affinity purification of IBPs using an ice-shell (Marshall et al. 2016). Apparatus used to capture IBPs from diverse mixtures of proteins and other solutes. In this system, the separating surface area was improved by isolating the IBPs into an ice shell formed within a rotating round-bottom flask, partially immersed in the sub-zero bath. In general, each ice-binding compound can be recovered from the liquid solution