title: Echinococcus granulosus: absorption of cycloleucine and alpha-aminoisobutyric acid by protoscoleces.
abstract: Protoscoleces of Echinococcus granulosus absorb the amino acids cycloleucine and alpha-aminoisobutyric acid (AIB) by a combination of mediated uptake and diffusion. After correcting for the latter, values for Kt and Vmax of 0.124 mM and 0.947 nmoles/mg protein/2 min for cycloleucine were calculated; corresponding values for AIB were 0.039 mM and 0.139 nmoles/mg protein/2 min. Both amino acids were accumulated against a concentration gradient and a comparison of Kt and Ki values determined in mutual inhibition experiments suggested that both cycloleucine and AIB share a common uptake locus (loci). Cycloleucine uptake was pH-dependent and could be inhibited by a variety of other amino acids. Neither D- nor L-proline inhibited cycloleucine absorption but D-methionine, D-alanine, D-leucine, D-valine and D-serine were much more effective inhibitors than their L-counterparts.
authors.forename: S A
authors.initials: SA
authors.lastname: Jeffs
authors.forename: C
authors.initials: C
authors.lastname: Arme
mesh_terms: D000042:Absorption; D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D000621:Aminoisobutyric Acids / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D003515:Cycloleucine / Q000378:metabolism*; D004058:Diffusion; D004446:Echinococcus / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D014633:Valine / Q000378:metabolism
chemical_list: D000596:Amino Acids; D000621:Aminoisobutyric Acids; D003515:Cycloleucine; C100049:2-aminoisobutyric acid; D012694:Serine; D011392:Proline; D008715:Methionine; D007930:Leucine; D014633:Valine; D000409:Alanine