Gas-tight triblock-copolymer membranes are converted to CO2 permeable by insertion of plant aquaporins

We demonstrate that membranes consisting of certain triblock-copolymers were tight for CO2. Using a novel approach, we provide evidence for aquaporin facilitated CO2 diffusion. Plant aquaporins obtained from heterologous expression were inserted into triblock copolymer membranes. These were employed to separate a chamber with a solution maintaining high CO2 concentrations from one with depleted CO2 concentrations. CO2 diffusion was detected by measuring the pH change resulting from membrane CO2 diffusion from one chamber to the other. An up to 21 fold increase in diffusion rate was determined. Besides the supply of this proof of principle, we could provide additional arguments in favour of protein facilitated CO2 diffusion to the vivid on-going debate about the principles of membrane gas diffusion in living cells.