11891257

pubmed:Citation

3

The initial rate of Fe(2+) movement across the inner envelope membrane of pea (Pisum sativum) chloroplasts was directly measured by stopped-flow spectrofluorometry using membrane vesicles loaded with the Fe(2+)-sensitive fluorophore, Phen Green SK. The rate of Fe(2+) transport was rapid, coming to equilibrium within 3s. The maximal rate and concentration dependence of Fe(2+) transport in predominantly right-side-out vesicles were nearly equivalent to those measured in largely inside-out vesicles. Fe(2+) transport was stimulated by an inwardly directed electrochemical proton gradient across right-side-out vesicles, an effect that was diminished by the addition of valinomycin in the presence of K(+). Fe(2+) transport was inhibited by Zn(2+), in a competitive manner, as well as by Cu(2+) and Mn(2+). These results indicate that inward-directed Fe(2+) transport across the chloroplast inner envelope occurs by a potential-stimulated uniport mechanism.

eng

IM

MEDLINE

0032-0889

Print

NLM

1022-30

pubmed-meshheading:11891257-Biological Transport, pubmed-meshheading:11891257-Cadmium, pubmed-meshheading:11891257-Cell Membrane, pubmed-meshheading:11891257-Chloroplasts, pubmed-meshheading:11891257-Copper, pubmed-meshheading:11891257-Ferrous Compounds, pubmed-meshheading:11891257-Fluorescence, pubmed-meshheading:11891257-Fluorescent Dyes, pubmed-meshheading:11891257-Hydrogen-Ion Concentration, pubmed-meshheading:11891257-Ion Transport, pubmed-meshheading:11891257-Kinetics, pubmed-meshheading:11891257-Manganese, pubmed-meshheading:11891257-Organic Chemicals, pubmed-meshheading:11891257-Peas, pubmed-meshheading:11891257-Potassium, pubmed-meshheading:11891257-Spectrometry, Fluorescence, pubmed-meshheading:11891257-Valinomycin, pubmed-meshheading:11891257-Zinc

Ferrous ion transport across chloroplast inner envelope membranes.

Journal Article, Research Support, U.S. Gov't, Non-P.H.S.