48] Microbial electron transport particle

Abstract

Publisher Summary An electron transport particle (ETP) from a microbial cell may be defined as any organized group of enzymes and cofactors which show a stoichiometric association and which carry out the complete oxidation of a metabolic substrate. The oxidation of succinate and DPNH by molecular oxygen is the major function found in electron transport particles from mammalian systems, and a particle of this type, which has been prepared from Azotobacter is described in the chapter. Similar particles may be prepared from other microbial sources. These particles are derived from the fragmented cell membrane or from extensions of the cell membrane into the interior of the cell. The oxidation of succinate or DPNH may not be the only criterion for defining an electron transport particle but it has been shown that the oxidation of malate is mediated by a flavoprotein, which is associated with the electron transport particle from M. phlei. Sonication of Escherichia coli yields heavy and light fragments, which do not have identical electron transport activity or quinone content. Active particles have also been obtained by sonication from Mycobacterium phlei, Haemophilus parainfluenzae, Bacillus stearothermophilus, and Bacillus subtilis .