Separation of Plant 6-Phosphogluconate Dehydrogenase (6PGDH) Isoforms by Non-denaturing Gel Electrophoresis

6-Phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44) catalyzes the third and irreversible reaction of the pentose phosphate pathway (PPP). It carries out the oxidative decarboxylation of the 6-phosphogluconate to yield ribulose-5-phosphate, carbon dioxide and NADPH. In higher plants, 6PGDH has several subcellular localizations including cytosol, chloroplast, mitochondria and peroxisomes ( Corpas et al., 1998 ; Krepinsky et al., 2001 ; Mateos et al., 2009 ; Fernández-Fernández and Corpas, 2016; Hölscher et al., 2016 ). Using Arabidopsis thaliana as plant model and sweet pepper (Capsicum annuum L.) fruits as a plant with agronomical interest, this protocol illustrates how to prepare the plant extracts for the separation of the potential 6PGDH isoforms by electrophoresis on 6% polyacrylamide non-denaturing gels. Thus, this method allows detecting three 6PGDH isoforms in Arabidopsis seedlings and two 6PGDH isoforms in sweet pepper fruits.