Annexin V binding perturbs the cardiolipin fluidity gradient in isolated mitochondria. Can it affect mitochondrial function?

The phosholipid bilayer fluidity of isolated mitochondria and phospholipid vesicles after calcium-dependent binding of annexin V was studied using EPR spectroscopy. The membranes were probed at different depths by alternatively using cardiolipin, phosphatidylcholine, or phosphatidylethanolamine spin labeled at position C-5 or C-12 or C-16 of the beta acyl chain. Computer-aided spectral titration facilitated observing and quantitating the EPR spectrum from phospholipid spin labels affected by annexin binding, and spectral mobility was calibrated by comparison with standard spectra scanned at various temperatures.

Cloning and characterisation of mtDBP, a DNA-binding protein which binds two distinct regions of sea urchin mitochondrial DNA.

The cDNA for the sea urchin mitochondrial D-loop-binding protein (mtDBP), a 40 kDa protein which binds two homologous regions of mitochondrial DNA (the D-loop region and the boundary between the oppositely transcribed ND5 and ND6 genes), has been cloned. Four different 3'-untranslated regions have been detected that are related to each other in pairs and do not contain the canonical polyadenylation signal. The in vitro synthesised mature protein (348 amino acids), deprived of the putative signal sequence, binds specifically to its DNA target sequence and produces a DNase I footprint identical to that given by the natural protein.

Inhibition of nucleoside diphosphate kinase in rat liver mitochondria by added 3'-azido-3'-deoxythymidine.

The effect of 3'-azido-3'-deoxythymidine on nucleoside diphosphate kinase of isolated rat liver mitochondria has been studied. This is done by monitoring the increase in the rate of oxygen uptake by nucleoside diphosphate (TDP, UDP, CDP or GDP) addition to mitochondria in state 4. It is shown that 3'-azido-3'-deoxythymidine inhibits the mitochondrial nucleoside diphosphate kinase in a competitive manner, with a Ki value of about 10 microM as measured for each tested nucleoside diphosphate.

Mitochondria as cell targets of AZT (zidovudine).

1. The subject of this review is the interaction between AZT (zidovudine) and mitochondria as described in papers dealing with AZT therapy both in AIDS patients and in model systems--that is, in cultured cells and in isolated mitochondria. 2.

Rat liver mitochondria can hydrolyse thiamine pyrophosphate to thiamine monophosphate which can cross the mitochondrial membrane in a carrier-mediated process.

We show here that TPP --> TMP conversion can take place in rat liver mitochondria. This occurs via the novel, putative TPP pyrophosphatase localised in the mitochondrial matrix, as shown both by digitonin titration and by an HPLC enzyme assay carried out on the mitochondrial matrix fraction. Certain features of the reaction, including the substrate and pH dependence, are reported.