CHARACTERIZATION OF NAD-DEPENDENT MALATE DEHYDROGENASES FROM SPINACH CHLOROPLASTS

摘要

Malate dehydrogenase (MDH) is one of three enzymes catalyzing the synthesis and oxidation of rnalate in plant cells, taking part in the regulation of redox and pH homeostasis. Chloroplast stroma contains both light, regulated NADP-MDH (EC.1.1.1.82) and NAD-MDH (E.G. 1.1.1.37) that is not redox regulated (for reviewsee Scheibe 2004). While the soluble form of the NAD-MDH is located in all of the cell compartments (Berkemeyer et al I998), the membrane-bound form was reported to be located in the innermitochondria! (Gross 1990). peroxisomal (Struglics et al 1993) and plasma membranes (Hadzi-Taskovic et al 1999). The inner chloroplast envelope regulates the transport of reducing and phosphorylat-ing equivalents between the chloroplast and other cell compartments. It has also been shown to contain electron carriers, components of the redox chain (Jager-Vottero et aS 1997) and enzymes involved in the synthesis, desaturation and degradation processes of lipids.