In the aerobic tricarboxylate cycle succinate is formed via oxidation of a-ketoglutarate, but anaerobically various bacteria form it via reduction of fumarate. The latter pathway was initially inferred to account for the large amounts of succinate and its derivative, propionate, produced in the fermentation of glycerol by propionic bacteria (l-4). Furthermore, fumarate was later shown to serve ...

Electron paramagnetic resonance (EPR) and near-infrared magnetic circular dichroism (MCD) have been used to identify the ligands to the cytochrome b556 component of succinate: ubiquinone oxidoreductase (succinate dehydrogenase) from Escherichia coli. The 'highly axial low spin' (HALS) EPR spectrum suggests bis(histidine) ligation of the heme with the histidines in a staggered configuration. The...

Frataxin deficiency is the main cause of Friedreich ataxia, an autosomal recessive neurodegenerative disorder. Frataxin function in mitochondria has not been fully explained yet. In this work, we show that Saccharomyces cerevisiae frataxin orthologue Yfh1p interacts physically with succinate dehydrogenase complex subunits Sdh1p and Sdh2p of the yeast mitochondrial electron transport chain and a...

It is counterintuitive that metabolic defects reducing ATP production can cause, rather than protect from, cancer. Yet this is precisely the case for familial paraganglioma, a form of neuroendocrine malignancy caused by loss of succinate dehydrogenase in the tricarboxylic acid cycle. Here we review biochemical, genetic, and epigenetic considerations in succinate dehydrogenase loss and present l...

We have developed a quantitative histochemical assay for measurement of succinate dehydrogenase (SDH) activity in single motoneurons. A computer image processing system was used to quantify the histochemical enzyme reaction product and to follow the time course of the reaction. The optimal concentration for each of the ingredients of the incubation medium for the SDH reaction was determined and...

Mitochondrial complex II, or succinate dehydrogenase, is a key enzymatic complex involved in both the tricarboxylic acid (TCA) cycle and oxidative phosphorylation as part of the mitochondrial respiratory chain. Germline succinate dehydrogenase subunit A (SDHA) mutations have been reported in a few patients with a classical mitochondrial neurodegenerative disease. Mutations in the genes encoding...

BACKGROUND Pituitary tumors, paragangliomas, and Cowden syndrome do not usually occur together. METHODS The synchronous presentation of papillary thyroid carcinoma and neck paraganglioma was revealed in a 43-year-old woman who had been diagnosed with a microprolactinoma one decade before and now presented with a constellation of characteristics that are components of Cowden syndrome, specific...

The succinate dehydrogenase consists of only four subunits, all nuclearly encoded, and is part of both the respiratory chain and the Krebs cycle. Mutations in the four genes encoding the subunits of the mitochondrial respiratory chain succinate dehydrogenase have been recently reported in human and shown to be associated with a wide spectrum of clinical presentations. Although a comparatively r...