The Photorespiratory Pathway of Leaf Peroxisomes

Abstract

Photorespiration is a light-dependent process that results in the uptake of O2 and the release of CO2. Photorespiration is linked to photosynthesis by the dual function of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) which uses the mutually competitive substrates CO2 and O2 for reaction with ribulose-1.5-bisphosphate (Rul.5BP). Oxygenation of ribulose-1.5-bisphosphate leads to the production of 2-P-glycolate, which is salvaged in the photorespiratory pathway (C2 cycle). Several enzymes of the photorespiratory pathway are localized in leaf peroxisomes and the recycling of 2-P-glycolate is the main function of leaf peroxisomes known so far. Apart from the photorespiratory C2 cycle, leaf peroxisomes have an important physiological role in the metabolism of active oxygen species (see Chapter 7), mediate fatty acid β-oxidation (Chapter 1 this volume; Gerhardt, 1981, 1983; Guhnemarm-Schafer and Kindl, 1995), and are involved in the biosynthesis of glycine betaine.