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Published on: September 28, 2016
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Determination of the Rate-Limiting Step in Fatty Acid Transport
Victoria Cheng1, Dylan R Kimball1, Dr John C Conboy1
1Department of Chemistry , University of Utah , 315 South 1400 East, RM 2020 , Salt Lake City , Utah 84112 , United States.
The Journal of Physical Chemistry. B
|July 24, 2019
Summary
Free fatty acid (FA) transport across membranes is key. This study used sum-frequency vibrational spectroscopy (SFVS) to show that FA desorption, not flip-flop, is the rate-limiting step in membrane transport.
Area of Science:
- Biophysics
- Membrane Biology
- Physical Chemistry
Background:
- Cellular free fatty acid (FA) transport is modeled in three steps: adsorption, translocation (flip-flop), and desorption.
- The rate-limiting step in FA transport remains debated, impacting cellular metabolism and signaling.
Purpose of the Study:
- To directly measure the rates of stearic acid (SA) flip-flop and desorption in lipid bilayers.
- To investigate the influence of SA on lipid bilayer physical properties and its effect on transport rates.
- To determine the rate-limiting step in protein-unassisted FA membrane transport.
Main Methods:
- Sum-frequency vibrational spectroscopy (SFVS) to directly measure flip-flop and desorption rates.
- Π-A isotherms to analyze the physical properties of stearic acid and DSPC mixtures.
- Planar supported lipid bilayers (PSLBs) and hybrid supported lipid bilayers (HSLBs) as model membrane systems.
Main Results:
- Stearic acid (SA) flip-flops independently of DSPC on faster timescales.
- SA alters the physical properties of DSPC lipid bilayers.
- SFVS enabled decoupled measurements of SA flip-flop and desorption rates in HSLBs.
Conclusions:
- Desorption is the rate-limiting step for protein-unassisted free fatty acid transport across membranes.
- Understanding FA transport dynamics is crucial for cellular function and disease research.
- SFVS provides a powerful tool for dissecting complex membrane transport mechanisms.
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