Structure, function and evolution of antifreeze proteins

Ewart, K. Vanya; Lin, Qingsong; Hew, Choy‐Leong

doi:10.1007/s000180050289

Cited by 230 publications

(160 citation statements)

References 80 publications

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“…In this energy-minimized structure, the oxygen atoms O [38] [27] is 4.552 Å. These distances are very close to the 4.52 Å found in the prism face of ice nuclei.…”

Section: Discussionsupporting

confidence: 64%

Inhibition of Ice Crystal Growth in Ice Cream Mix by Gelatin Hydrolysate

Damodaran

2007

J. Agric. Food Chem.

124

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The inhibition of ice crystal growth in ice cream mix by gelatin hydrolysate produced by papain action was studied. The ice crystal growth was monitored by thermal cycling between -14 and -12°C at a rate of one cycle per 3 min. It is shown that the hydrolysate fraction containing peptides in the molecular weight range of about 2000 -5000 Da exhibited the highest inhibitory activity on ice crystal growth in ice cream mix, whereas fractions containing peptides greater than 7000 Da did not inhibit ice crystal growth. The size distribution of gelatin peptides formed in the hydrolysate was influenced by the pH of hydrolysis. The optimum hydrolysis conditions for producing peptides with maximum ice crystal growth inhibitory activity was pH 7 at 37°C for 10 min at a papain to gelatin ratio of 1:100. However, this may depend on the type and source of gelatin. The possible mechanism of ice crystal growth inhibition by peptides from gelatin is discussed. Molecular modeling of model gelatin peptides revealed that they form an oxygen triad plane at the C-terminus with oxygen-oxygen distances similar to those found in ice nuclei. Binding of this oxygen triad plane to the prism face of ice nuclei via hydrogen bonding appears to be the mechanism by which gelatin hydrolysate might be inhibiting ice crystal growth in ice cream mix.

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“…In this energy-minimized structure, the oxygen atoms O [38] [27] is 4.552 Å. These distances are very close to the 4.52 Å found in the prism face of ice nuclei.…”

Section: Discussionsupporting

confidence: 64%

Inhibition of Ice Crystal Growth in Ice Cream Mix by Gelatin Hydrolysate

Damodaran

2007

J. Agric. Food Chem.

124

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“…Although direct comparisons between the conformation of residues 1-10 of SS3 and SS8 cannot be made, our results suggest that the first 10 residues of SS3 are aligned approximately parallel to the ␣-helix formed by residues 11-33, with no significant deviation similar to that predicted for SS8 (35). Further structural constraints derived from 15 N, 13 C-labeled protein (including 13 C-X residual dipolar couplings) are required to fully refine the structure.…”

Section: Discussionmentioning

confidence: 73%

Type I Shorthorn Sculpin Antifreeze Protein

Fairley¹,

Westman²,

Pham³

et al. 2002

Journal of Biological Chemistry

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A number of structurally diverse classes of "antifreeze" proteins that allow fish to survive in sub-zero ice-laden waters have been isolated from the blood plasma of cold water teleosts. However, despite receiving a great deal of attention, the one or more mechanisms through which these proteins act are not fully understood. In this report we have synthesized a type I antifreeze polypeptide (AFP) from the shorthorn sculpin Myoxocephalus scorpius using recombinant methods. Construction of a synthetic gene with optimized codon usage and expression as a glutathione S-transferase fusion protein followed by purification yielded milligram amounts of polypeptide with two extra residues appended to the N terminus. Circular dichroism and NMR experiments, including residual dipolar coupling measurements on a 15 N-labeled recombinant polypeptide, show that the polypeptides are ␣-helical with the first four residues being more flexible than the remainder of the sequence. Both the recombinant and synthetic polypeptides modify ice growth, forming facetted crystals just below the freezing point, but display negligible thermal hysteresis. Acetylation of Lys-10, Lys-20, and Lys-21 as well as the N terminus of the recombinant polypeptide gave a derivative that displays both thermal hysteresis (0.4°C at 15 mg/ml) and ice crystal faceting. These results confirm that the N terminus of wild-type polypeptide is functionally important and support our previously proposed mechanism for all type I proteins, in which the hydrophobic face is oriented toward the ice at the ice/water interface.The type I AFPs 1 found in the blood of cold water teleosts (1-3) have attracted significant interest, due to the potential applications of such compounds in biotechnology and medicine (4 -9). These compounds are alanine-rich ␣-helical proteins of 33-47 residues in length (for reviews see Refs. 10 -13). Although 14 type I proteins have been identified in nature (summarized in Ref. 12), almost all studies to date have centered on HPLC6, the 37-residue protein from the winter flounder (see Table I below) (14). This protein is characterized as an AFP, because it modifies both the rate and shape of ice crystal growth and displays thermal hysteresis, i.e. a positive difference between the ice growth temperature and the equilibrium melting temperature of ice.During the last decade, significant progress has been made in elucidating the structural features of HPLC6 that are required to give antifreeze activity. Structure-activity studies have identified the importance of the Thr residues at positions 2, 13, 24, and 35 plus surrounding residues, for ice growth inhibition activity. Although the Thr residues were assumed to be involved in hydrogen-bonding interactions with ice for many years (15-19), more recent mutations have identified the hydrophobicity provided by the ␥-methyl group of Thr as a key factor related to the ability to inhibit ice growth (20 -24). Hydrogen bonding and other roles for the surrounding residues have also been considered (24 -29). Howe...

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“…In order to overcome the detrimental effect of low temperatures, psychrophiles have developed various adaptive strategies. One of the strategies used in order to withstand temperatures below freezing is the protection of the cells from ice formation by the synthesis of antifreeze molecules and cryoprotectors (12). Another problem is the decrease in membrane fluidity with temperature.…”

Section: Psychrophilic Organismsmentioning

confidence: 99%

Extreme catalysts from low-temperature environments

Hoyoux

Blaise

Collins

et al. 2004

Journal of Bioscience and Bioengineering

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Cold-loving or psychrophilic organisms are widely distributed in nature as a large part of the earth's surface is at temperatures around 0°C. To maintain metabolic rates and to prosper in cold environments, these extremophilic organisms have developed a vast array of adaptations. One main adaptive strategy developed in order to cope with the reduction of chemical reaction rates induced by low temperatures is the synthesis of cold-adapted or psychrophilic enzymes. These enzymes are characterized by a high catalytic activity at low temperatures associated with a low thermal stability. A study of protein adaptation strategies suggests that the high activity of psychrophilic enzymes could be achieved by the destabilization of the active site, allowing the catalytic center to be more flexible at low temperatures, whereas other protein regions may be destabilized or as rigid as their mesophilic counterparts. Due to these particular properties, psychrophilic enzymes offer a high potential not only for fundamental research but also for biotechnological applications.[Key words: psychrophile, extremophiles, cold adaptation, enzyme kinetics, flexibility strategy]Life under low-temperature conditions was identified as early as 1840 by Hooker, who observed that algae were associated with sea ice. In 1887, Forster was the first who reported that microorganisms isolated from fish could grow well at 0°C (1). The term "psychrophilic" was first used in 1902 by Schmidt-Nielsen to describe such cold-adapted organisms (2). Psychrophile is defined as an organism, prokaryotic or eukaryotic, living permanently at temperatures close to the freezing point of water in thermal equilibrium with the medium. Thus psychrophiles are numerous, including a large range of species of gram-positive and gram-negative bacteria, yeast, algae, marine invertebrates, insects and polar fish, and are widely distributed (3). Psychrophiles have developed mechanisms of adaptation to temperature including a huge range of structural and physiological adjustments in order to cope with the deleterious effect of low temperatures. Indeed, they display metabolic fluxes at low temperatures that are more or less comparable to those exhibited by closely related mesophiles living at moderate temperatures (4-6). This is explained by the capability of these psychrophilic organisms to produce "cold-adapted" enzymes which are able to cope with the reduction of chemical reaction rates induced by low temperatures. However, most cellular adaptations to low temperatures and the underlying molecular mechanisms are not fully understood and are still being investigated. Moreover, a study of proteins and enzymes from cold-adapted organisms is not only useful in the understanding of some general processes related to the protein structure and function but also in protein folding investigations. In addition, cold-active and heat-labile psychrophilic enzymes possess an interesting biotechnological potential.

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Structure, function and evolution of antifreeze proteins

Cited by 230 publications

References 80 publications

Inhibition of Ice Crystal Growth in Ice Cream Mix by Gelatin Hydrolysate

Inhibition of Ice Crystal Growth in Ice Cream Mix by Gelatin Hydrolysate

Type I Shorthorn Sculpin Antifreeze Protein

Extreme catalysts from low-temperature environments

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