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Towards a green hydrate inhibitor: imaging antifreeze proteins on clathrates.

Gordienko R, Ohno H, Singh VK, Jia Z, Ripmeester JA, Walker VK - PLoS ONE (2010)

Bottom Line: We show here that antifreeze proteins (AFPs) possess the ability to modify structure II (sII) tetrahydrofuran (THF) hydrate crystal morphologies by adhering to the hydrate surface and inhibiting growth in a similar fashion to the kinetic inhibitor poly-N-vinylpyrrolidone (PVP).The effects of AFPs on the formation and growth rate of high-pressure sII gas mix hydrate demonstrated that AFPs are superior hydrate inhibitors compared to PVP.These results indicate that AFPs may be suitable for the study of new inhibitor systems and represent an important step towards the development of biologically-based hydrate inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Queen's University, Kingston, Ontario, Canada.

ABSTRACT
The formation of hydrate plugs in oil and gas pipelines is a serious industrial problem and recently there has been an increased interest in the use of alternative hydrate inhibitors as substitutes for thermodynamic inhibitors like methanol. We show here that antifreeze proteins (AFPs) possess the ability to modify structure II (sII) tetrahydrofuran (THF) hydrate crystal morphologies by adhering to the hydrate surface and inhibiting growth in a similar fashion to the kinetic inhibitor poly-N-vinylpyrrolidone (PVP). The effects of AFPs on the formation and growth rate of high-pressure sII gas mix hydrate demonstrated that AFPs are superior hydrate inhibitors compared to PVP. These results indicate that AFPs may be suitable for the study of new inhibitor systems and represent an important step towards the development of biologically-based hydrate inhibitors.

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Related in: MedlinePlus

Levels of AFP adsorbed into THF hydrate.Differences in the average µmoles of protein adsorbed per gram of THF hydrate crystal (µmoles/g-crystal) between LpAFP-GFP (horizontal lines), Type III AFP-GFP (vertical lines) and GFP (solid) are plotted as a function of protein concentration (µM). Bars indicate standard deviation. Statistical significance between each data group is indicated by letters A–C, where identical letters indicate no statistical difference.
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pone-0008953-g003: Levels of AFP adsorbed into THF hydrate.Differences in the average µmoles of protein adsorbed per gram of THF hydrate crystal (µmoles/g-crystal) between LpAFP-GFP (horizontal lines), Type III AFP-GFP (vertical lines) and GFP (solid) are plotted as a function of protein concentration (µM). Bars indicate standard deviation. Statistical significance between each data group is indicated by letters A–C, where identical letters indicate no statistical difference.

Mentions: Polycrystalline THF hydrate crystals grown in the presence of GFP-tagged AFPs were obviously fluorescent green under UV illumination (Fig. 2). Conversely, when hydrate was grown in the presence of recombinant GFP alone, the hydrates were uniformly dark. In an effort to quantify the adsorption, the hydrates were melted and assayed for adsorbed protein (µmoles of recombinant protein per gram of crystal, Fig. 3). For both purified LpAFP-GFP and Type III AFP-GFP fusion proteins, there was a linear correlation between the amount of protein adsorbed into the growing THF hydrate and the concentration of the protein in the THF solution. At lower concentrations (2 and 4 µM) more Type III AFP-GFP appeared to bind than LpAFP-GFP. At higher concentrations (8 and 16 µM) more LpAFP-GFP adsorbed, to an average of 42% more, than Type III AFP. All differences between the two AFP-GFPs were statistically significant. In contrast, no adsorption of GFP was detected in the crystals at any concentration, with the exception of 2 µM, where an average of 7.9×10−5 µmoles/g-crystal was detected. At all other concentrations, differences in the amounts of GFP bound compared to the two AFP-GFPs were statistically significant.


Towards a green hydrate inhibitor: imaging antifreeze proteins on clathrates.

Gordienko R, Ohno H, Singh VK, Jia Z, Ripmeester JA, Walker VK - PLoS ONE (2010)

Levels of AFP adsorbed into THF hydrate.Differences in the average µmoles of protein adsorbed per gram of THF hydrate crystal (µmoles/g-crystal) between LpAFP-GFP (horizontal lines), Type III AFP-GFP (vertical lines) and GFP (solid) are plotted as a function of protein concentration (µM). Bars indicate standard deviation. Statistical significance between each data group is indicated by letters A–C, where identical letters indicate no statistical difference.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2820087&req=5

pone-0008953-g003: Levels of AFP adsorbed into THF hydrate.Differences in the average µmoles of protein adsorbed per gram of THF hydrate crystal (µmoles/g-crystal) between LpAFP-GFP (horizontal lines), Type III AFP-GFP (vertical lines) and GFP (solid) are plotted as a function of protein concentration (µM). Bars indicate standard deviation. Statistical significance between each data group is indicated by letters A–C, where identical letters indicate no statistical difference.
Mentions: Polycrystalline THF hydrate crystals grown in the presence of GFP-tagged AFPs were obviously fluorescent green under UV illumination (Fig. 2). Conversely, when hydrate was grown in the presence of recombinant GFP alone, the hydrates were uniformly dark. In an effort to quantify the adsorption, the hydrates were melted and assayed for adsorbed protein (µmoles of recombinant protein per gram of crystal, Fig. 3). For both purified LpAFP-GFP and Type III AFP-GFP fusion proteins, there was a linear correlation between the amount of protein adsorbed into the growing THF hydrate and the concentration of the protein in the THF solution. At lower concentrations (2 and 4 µM) more Type III AFP-GFP appeared to bind than LpAFP-GFP. At higher concentrations (8 and 16 µM) more LpAFP-GFP adsorbed, to an average of 42% more, than Type III AFP. All differences between the two AFP-GFPs were statistically significant. In contrast, no adsorption of GFP was detected in the crystals at any concentration, with the exception of 2 µM, where an average of 7.9×10−5 µmoles/g-crystal was detected. At all other concentrations, differences in the amounts of GFP bound compared to the two AFP-GFPs were statistically significant.

Bottom Line: We show here that antifreeze proteins (AFPs) possess the ability to modify structure II (sII) tetrahydrofuran (THF) hydrate crystal morphologies by adhering to the hydrate surface and inhibiting growth in a similar fashion to the kinetic inhibitor poly-N-vinylpyrrolidone (PVP).The effects of AFPs on the formation and growth rate of high-pressure sII gas mix hydrate demonstrated that AFPs are superior hydrate inhibitors compared to PVP.These results indicate that AFPs may be suitable for the study of new inhibitor systems and represent an important step towards the development of biologically-based hydrate inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Queen's University, Kingston, Ontario, Canada.

ABSTRACT
The formation of hydrate plugs in oil and gas pipelines is a serious industrial problem and recently there has been an increased interest in the use of alternative hydrate inhibitors as substitutes for thermodynamic inhibitors like methanol. We show here that antifreeze proteins (AFPs) possess the ability to modify structure II (sII) tetrahydrofuran (THF) hydrate crystal morphologies by adhering to the hydrate surface and inhibiting growth in a similar fashion to the kinetic inhibitor poly-N-vinylpyrrolidone (PVP). The effects of AFPs on the formation and growth rate of high-pressure sII gas mix hydrate demonstrated that AFPs are superior hydrate inhibitors compared to PVP. These results indicate that AFPs may be suitable for the study of new inhibitor systems and represent an important step towards the development of biologically-based hydrate inhibitors.

Show MeSH
Related in: MedlinePlus