Membrane transport of amino acid enantiomers in protoscoleces of Echinococcus granulosus (Cestoda).
Protoscoleces of Echinococcus granulosus absorb both L- and D-alanine. Concentration ratios exceed 1 with values for D-alanine exceeding those for the L-isomer, suggesting that both are absorbed by active mechanisms. Uptake of both isomers involves both diffusion and carrier-mediated components. Values for the diffusion component (Kd) for L- and D-alanine were 0.21 and 0.38 nmol mg-1 protein/1.5 min mM-1 respectively, and values for Kt, the transport constants, 0.17 mM and 0.21 mM respectively. Uptake of both isomers was inhibited competitively by a number of other amino acids.
Allen
J T
JT
Department of Biological Sciences, University of Keele, Staffordshire, U.K.
Arme
C
C
D000409:Alanine / Q000493:pharmacokinetics*; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D004446:Echinococcus / Q000378:metabolism*; D007700:Kinetics; D013237:Stereoisomerism
D000596:Amino Acids; D000409:Alanine