Membranes for artificial photosynthesis

2017 ◽  
Vol 10 (6) ◽  
pp. 1320-1338 ◽  
Author(s):  
Sakineh Chabi ◽  
Kimberly M. Papadantonakis ◽  
Nathan S. Lewis ◽  
Michael S. Freund
Keyword(s):  
Charge Transport ◽  
Artificial Photosynthesis ◽  
Electrochemical Potential ◽  
Potential Gradients

Membrane-based architectures enable optimization of charge transport and electrochemical potential gradients in artificial photosynthesis.

scholarly journals Function Trumps Form in Two Sugar Symporters, LacY and vSGLT

2021 ◽  
Vol 22 (7) ◽  
pp. 3572
Author(s):  
Jeff Abramson ◽  
Ernest M. Wright
Keyword(s):  
Binding Site ◽  
Sugar Transport ◽  
Electrochemical Potential ◽  
Inverted Repeats ◽  
Side Chains ◽  
Transmembrane Helices ◽  
Central Cavity ◽  
Potential Gradients ◽  
Sodium Binding ◽  
Major Facilitator

Active transport of sugars into bacteria occurs through symporters driven by ion gradients. LacY is the most well-studied proton sugar symporter, whereas vSGLT is the most characterized sodium sugar symporter. These are members of the major facilitator (MFS) and the amino acid-Polyamine organocation (APS) transporter superfamilies. While there is no structural homology between these transporters, they operate by a similar mechanism. They are nano-machines driven by their respective ion electrochemical potential gradients across the membrane. LacY has 12 transmembrane helices (TMs) organized in two 6-TM bundles, each containing two 3-helix TM repeats. vSGLT has a core structure of 10 TM helices organized in two inverted repeats (TM 1–5 and TM 6–10). In each case, a single sugar is bound in a central cavity and sugar selectivity is determined by hydrogen- and hydrophobic- bonding with side chains in the binding site. In vSGLT, the sodium-binding site is formed through coordination with carbonyl- and hydroxyl-oxygens from neighboring side chains, whereas in LacY the proton (H3O+) site is thought to be a single glutamate residue (Glu325). The remaining challenge for both transporters is to determine how ion electrochemical potential gradients drive uphill sugar transport.

Tuning Charge Transport at the Interface between Indium Phosphide and a Polypyrrole−Phosphomolybdate Hybrid through Manipulation of Electrochemical Potential

2002 ◽  
Vol 106 (7) ◽  
pp. 1622-1636 ◽  
Author(s):  
Carrie Daniels-Hafer ◽  
Meehae Jang ◽  
Shannon W. Boettcher ◽  
Robert G. Danner ◽  
Mark C. Lonergan
Keyword(s):  
Indium Phosphide ◽  
Charge Transport ◽  
Electrochemical Potential

Potassium transport by turtle colon: active secretion and active absorption

1984 ◽  
Vol 246 (3) ◽  
pp. C315-C322 ◽  
Author(s):  
D. R. Halm ◽  
D. C. Dawson
Keyword(s):  
Simple Model ◽  
Short Circuit ◽  
Potassium Transport ◽  
Electrochemical Potential ◽  
Free Solution ◽  
Active Secretion ◽  
Basolateral Membranes ◽  
Potential Gradients ◽  
Absorptive Flux ◽  
K Transport

Measurement of transepithelial potassium fluxes in the absence of transmural electrochemical potential gradients showed that the isolated turtle colon can actively absorb and actively secrete K+. Under short-circuit conditions the active secretory flow was inhibited by mucosal amiloride, whereas the absorptive flow was unaffected by the diuretic. The effects of ouabain and barium on secretory flow were consistent with a simple model involving basolateral uptake by an Na+-K+-ATPase and conductive exist across the apical and basolateral membranes. The active absorptive flux was blocked by mucosal ouabain and by serosal barium. The opposing active flows clearly represented cellular K+ transport, whereas paracellular K+ flows behaved as expected for a free-solution shunt.

Sign in / Sign up

Export Citation Format

Share Document