Premium
Carrier mediated uptake of dehydroascorbate into higher plant plasma membrane vesicles shows trans‐stimulation
Author(s) -
Horemans Nele,
Asard Han,
Caubergs Roland Julien
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)01534-2
Subject(s) - vesicle , ferricyanide , membrane , chemistry , kinetics , efflux , biochemistry , glutathione , stimulation , biophysics , biology , enzyme , neuroscience , physics , quantum mechanics
The activity of the ascorbate (Asc) carrier of purified Phaseolus plasma membranes is demonstrated to be highly stimulated when membrane vesicles are preloaded with Asc. Asc transport is inhibited by DTT but is not affected by glutathione or ferricyanide, indicating that dehydroascorbate (DHA) is the preferred species for uptake. Asc transport in the loaded vesicles showed saturable kinetics with an apparent affinity constant of 24 μM and maximal uptake rate of 94 pmol/mg/min. Addition of DHA stimulated the efflux of Asc molecules from the loaded vesicles. Together these results suggest the presence of an Asc/DHA exchange mechanism in higher plant plasma membranes.