The alternative oxidase in roots of Poa species

Abstract

The main function of respiration is the production of energy-rich molecules (ATP). A major part (up to 60%) of the respiration in plants can occur via the nonphosphorylating alternative pathway, even under conditions when the sugar concentration is low. This suggests that the energetically 'wasteful' alternative pathway has a crucial function in plant metabolism. This alternative pathway does not produce energy in the form of ATP. The proposed function of the alternative pathway is the prevention of the production of excessive amounts of oxygen free radicals. The alternative pathway consists of only one protein, the alternative oxidase (AOX). This protein has been studied in detail in isolated mitochondria and several regulatory mechanisms have been discovered (pyruvate, reduction state of the protein, substrate concentration). This thesis analyses the role of these putative regulatory mechanisms in modifying the altrenative oxidase activity in intact roots of a range of grasses.