Preliminary evidence on existence of transplasma membrane electron transport in Entamoeba histolytica trophozoites: a key mechanism for maintaining optimal redox balance.

Entamoeba histolytica, an amitochondriate parasitic protist, was demonstrated to be capable of reducing the oxidized form of alpha-lipoic acid, a non permeable electron acceptor outside the plasma membrane. This transmembrane reduction of non permeable electron acceptors with redox potentials ranging from -290 mV to +360 mV takes place at neutral pH. The transmembrane reduction of non permeable electron acceptors was not inhibited by mitochondrial electron transport inhibitors such as antimycin A, rotenone, cyanide and azide.

Characterization of the redox components of transplasma membrane electron transport system from Leishmania donovani promastigotes.

An investigation has been made of the points of coupling of four nonpermeable electron acceptors e.g., alpha-lipoic acid (ALA), 5,5'-dithiobis (2-nitroaniline-N-sulphonic acid) (DTNS), 1,2-naphthoquinone-4-sulphonic acid (NQSA) and ferricyanide which are mainly reduced via an interaction with the redox sites present in the plasma membrane of Leishmania donovani promastigotes.