Regulation of Aquaporin Z osmotic permeability in ABA tri-block copolymer

Wenyuan Xie; Jason Wei Jun Low; Arunmozhiarasi Armugam; Kandiah Jeyaseelan; Yen Wah Tong; Wenyuan Xie; Jason Wei Jun Low; Arunmozhiarasi Armugam; Kandiah Jeyaseelan; Yen Wah Tong

doi:10.3934/biophy.2015.3.381

AIMS Biophysics

2015, Volume 2, Issue 3: 381-397. doi: 10.3934/biophy.2015.3.381

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Regulation of Aquaporin Z osmotic permeability in ABA tri-block copolymer

1.
NUS Environmental Research Institute (NERI), National University of Singapore #02-01, T-Lab Building 5A Engineering Drive 1, Singapore 117411;
2.
Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore 117597;
3.
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585

Received: 15 May 2015 Accepted: 20 August 2015 Published: 31 August 2015

Aquaporins are transmembrane water channel proteins present in biological plasma membranes that aid in biological water filtration processes by transporting water molecules through at high speeds, while selectively blocking out other kinds of solutes. Aquaporin Z incorporated biomimetic membranes are envisaged to overcome the problem of high pressure needed, and holds great potential for use in water purification processes, giving high flux while keeping energy consumption low. The functionality of aquaporin Z in terms of osmotic permeability might be regulated by factors such as pH, temperature, crosslinking and hydrophobic thickness of the reconstituted bilayers. Hence, we reconstituted aquaporin Z into vesicles that are made from a series of amphiphilic block copolymers PMOXA-PDMS-PMOXAs with various hydrophobic molecular weights. The osmotic permeability of aquaporin Z in these vesicles was determined through a stopped-flow spectroscopy. In addition, the temperature and pH value of the vesicle solutions were adjusted within wide ranges to investigate the regulation of osmotic permeability of aquaporin Z through external conditions. Our results show that aquaporin Z permeability was enhanced by hydrophobic mismatch. In addition, the water filtration mechanism of aquaporin Z is significantly affected by the concentration of H⁺ and OH^- ions.
- aquaporin Z,
- biomimetic membranes,
- osmotic permeability,
- pH,
- hydrophobic mismatch
Citation: Wenyuan Xie, Jason Wei Jun Low, Arunmozhiarasi Armugam, Kandiah Jeyaseelan, Yen Wah Tong. Regulation of Aquaporin Z osmotic permeability in ABA tri-block copolymer[J]. AIMS Biophysics, 2015, 2(3): 381-397. doi: 10.3934/biophy.2015.3.381

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Abstract

Aquaporins are transmembrane water channel proteins present in biological plasma membranes that aid in biological water filtration processes by transporting water molecules through at high speeds, while selectively blocking out other kinds of solutes. Aquaporin Z incorporated biomimetic membranes are envisaged to overcome the problem of high pressure needed, and holds great potential for use in water purification processes, giving high flux while keeping energy consumption low. The functionality of aquaporin Z in terms of osmotic permeability might be regulated by factors such as pH, temperature, crosslinking and hydrophobic thickness of the reconstituted bilayers. Hence, we reconstituted aquaporin Z into vesicles that are made from a series of amphiphilic block copolymers PMOXA-PDMS-PMOXAs with various hydrophobic molecular weights. The osmotic permeability of aquaporin Z in these vesicles was determined through a stopped-flow spectroscopy. In addition, the temperature and pH value of the vesicle solutions were adjusted within wide ranges to investigate the regulation of osmotic permeability of aquaporin Z through external conditions. Our results show that aquaporin Z permeability was enhanced by hydrophobic mismatch. In addition, the water filtration mechanism of aquaporin Z is significantly affected by the concentration of H⁺ and OH^- ions.

References

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