Development of biomimetic, hybrid protein-synthetic membranes: determining protein insertion efficiency, membrane material suitability and relevance of aquaporin Z

Marincel Payne, Michelle K.

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https://hdl.handle.net/2142/99466 Copy

Description

Title

Development of biomimetic, hybrid protein-synthetic membranes: determining protein insertion efficiency, membrane material suitability and relevance of aquaporin Z

Author(s)

Marincel Payne, Michelle K.

Issue Date

2017-09-19

Director of Research (if dissertation) or Advisor (if thesis)

Zilles, Julie L.

Doctoral Committee Chair(s)

Zilles, Julie L.

Committee Member(s)

• Clark, Mark M.
• Fitch, Mark W
• Werth, Charles J.

Department of Study

Civil & Environmental Eng

Discipline

Environ Engr in Civil Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Aquaporin
• Aquaporin Z (AqpZ)
• Biomimetic
• Lipid
• Polymer
• Insertion efficiency

Abstract

Biomimetic membranes are designed to mimic the selective permeability of cell membranes, and can be engineered for a multitude of environmental applications including water purification, remediation, and sensing. Biomimetic membranes consist of membrane proteins, such as the bacterial water channel protein aquaporin Z (AqpZ), embedded in a lipid bilayer or a polymer that mimics a cell’s natural lipid bilayer. Permeability and stability pose critical barriers to implementation of biomimetic AqpZ-based membranes. To achieve maximum permeability, it is essential to understand the relationship between protein insertion and membrane permeability. This work introduces a method using fluorescence correlation spectroscopy to quantify the number of AqpZ embedded in the membrane. This work demonstrates that membrane permeability is a function of protein insertion and that detergent inhibits protein insertion. Substantial variation was observed in protein insertion and permeability between protein batches, perhaps due to differences in the multimeric state of the protein. For many applications, biomimetic technologies will only be pursued if they can be formed into planar sheets and if they remain stable under environmental or membrane cleaning stress conditions. This work provides proof of concept for the synthesis of solid-supported, planar mixed lipid-polymer membranes. While lipid and polymer membranes both insert proteins, lipids are more readily available and more closely mimic natural cell membranes. However, polymer improves vesicle toughness and stability. The mixed lipid-polymer membranes I created exhibited the desirable characteristics of both lipid and polymer membranes. I also demonstrated that in Escherichia coli, the presence of AqpZ increased permeability at neutral pH, and reduced survival under acid shock conditions. These findings may suggest possible physiological relevance for AqpZ. Highly permeable and selective biomimetic membranes are a promising technology for water purification, and understanding their formation and properties are crucial for development and implementation. Development of hybrid protein-synthetic membranes for water treatment will allow for small energy savings. More importantly, these membranes will make it more feasible to treat challenging water sources and encourage water reuse.

Graduation Semester

2017-12

Type of Resource

text

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http://hdl.handle.net/2142/99466

Copyright and License Information

Copyright 2017 Michelle Marincel Payne

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