ISSN:
1435-1463
Keywords:
L-threo-3, 4-dihydroxyphenylserine
;
uptake
;
human brain synaptosomes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Out of four diastereoisomers of 3,4-dihydroxyphenylserine (DOPS), L-threo- and L-erythro-isomer were found to be taken up into human brain synaptosomes. The uptake of L-threo-DOPS was dependent on the temperature and sensitive to the metabolic inhibitors. The L-threo-DOPS uptake proved to be saturable and carrier-mediated transport with two different kinetic characteristics; a high-affinity and low-capacity and a low-affinity and high-capacity system. The apparent Km values of these two systems were obtained to be 28.6ΜM and 2.47 mM, respectively. The high-affinity transport was inhibited by glycine, L-tyrosine, L-proline, L-serine, L-Dopa, L-tryptophan, and L-phenylalanine. The inhibition by L-tyrosine was competitive in regard to L-threo-DOPS. The L-threo-DOPS uptake was inhibited by 2,4-dinitrophenol, sodium cyanide and other uncouplers of oxidative phosphorylation and by ouabain, an inhibitor of Na+, K+-ATPase, indicating that the uptake is coupled to ATP hydrolysis. On the other hand, L-threo-DOPS uptake by the low-affinity systerm was not inhibited by metabolic inhibitors, indicating that it may be facilitated diffusion common to high concentrations of L-amino acids.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01252508
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