Abstract
“Metallo-carriers” mediate membrane transport of amino acid and oligopeptide derivative anions, providing new chemical analogues to biological amino acid transport and prototype for anion-separation membrane. Appropriate choice of metallo-carriers could allow accurate control of transport efficiency and selectivity.
Using transition metal complex carriers, Gly- and Ala-derivatives are much more effectively transported than Phe- and Leu-derivatives via “antiport mechanism”. Their transport properties are significantly determined by the natures of ligand molecule, central metal cation, and antiport anion. Active transport of amino acid derivatives is also achieved by some metallo-carriers.
Macrocyclic crown ether-alkali metal cation complex carriers exhibite marked contrasts to the transition metal complex carriers in the anion transport process. They selectively transport Phe- and Leu-derivatives via “symport mechanism”. As well as crown ether and cryptand compounds, some linear polyethers offer specific transport of amino acid derivatives.
In addition to transportation, such artificial carriers perform other interesting functions : Highly selective hydrolysis of amino acid esters is realized in synthetic carrier-functionalized membrane system. Further extensions may be anticipated in the wider related fields.
