Integrating classical and alternative respiratory pathway

Abstract

Respiratory pathways are vital for plant carbon and energy metabolism, which is the main use of most assimilated carbohydrates. Most respiratory pathways are very well established, the prominent being glycolysis in cytosol and the tricarboxylic acid (TCA) cycle, which occurs in the matrix of mitochondria coupled with the electron transport chain (ETC) which functions along the inner mitochondrial membrane. This chapter integrates such alternative respiratory pathways with components of the classical oxidative-phosphorylative pathways. Mitochondrial electron transport generates ATP by using the reducing equivalents derived through the operation of the TCA-cycle. Currently most research on alternative electron transfer is focused on nonphosphorylating bypass mechanisms: a second oxidase – the alternative oxidase (AOX), an external NAD (P) H dehydrogenases in the first part of ETC, and also plant uncoupling mitochondrial proteins (PUCPs). Electron transfer flavoprotein (ETF) is an electron acceptor for at least nine mitochondrial matrix flavoprotein dehydrogenases.