A new class of carrier, lipophilic copper complex, mediated active and passive transport of a variety of amino acid derivatives as carboxylate anion.
Carrier-mediated transport of amino acid derivatives plays essential roles in many biochemical processes. 1) It is very important to construct the model system of biological transport not only for simulating the biochemical systems, but also for developing a new methodology in the separation science. Although some kinds of polyethers 2) have been shown to transport ammonium cations derived from amino acids, we have known only a few synthetic carriers 3) for transporting amino acids as carboxylate anion, which may display largely different transport behaviors from those of previously reported cation-carriers.
Here we report that a new type of lipophilic copper complex carrier 1 e successfully mediated active and passive transport of amino acid derivatives.
In the present system (see Figure), metal complex, composed of neutral ligand CL), bound carboxylate anion (S-) at interface of aqueous phase I and CH2C12 membrane. The coordinated carboxylate was carried through CH2C12 membrane, and released into the aqueous phase II. The antiport anion (X-) was also transported in the opposite direction. The concentration gradient of antiport anion could drive active and passive transport of amino acid derivatives.
We examined four lipophilic copper complexes, l_, 2, 2, and 2, and trioctylmethyl-ammonium chloride 5 as anion carrier. The copper complex 1 was obtained
We confirmed that antiport anion was also transported in the opposite direction by using C104-instead of Cl-.
Under the employed conditions (see Table , ca. 7% of copper ion was leaked from membrane into aqueous phases after 12 h.