THE LEAF PEROXISOMAL FORM (MFP-IV) OF MULTIFUNCTIONAL PROTEIN FUNCTIONING IN FATTY-ACID BETA-OXIDATION

We have purified for the first time from green leaves a multifunctiona l protein (MFP) involved in fatty acid beta-oxidation. The protein, de signated MFP IV, was extracted from green leaves of three-week-old cuc umber (Cucumis sativus L.) plants. Chromatography on cation exchanger, separation on hydroxylapatite, and fast-protein liquid chromatography on Phenylsuperose led to a more than 7000-fold purification and to th e isolation of an apparently homogeneous 80-kDa monomeric protein. Thi s protein is immunologically related to the glyoxysomal MFP II, as evi denced by immunodecoration with antiserum raised against MFP II. Compa rison of molecular masses of all MFPs presently known revealed that th e MFP prepared from green leaves (MFP IV) is distinct from MFP II (76. 5 kDa) and MFP I (74 kDa) from dark-grown cotyledons. By including oth er properties in this comparison, we demonstrated that MFP IV can also be distinguished from the glyoxysomal MFP III (81 kDa) and the bacter ially expressed MFP-a (80 kDa). Moreover, MFP IV is a constituent of l eaf peroxisomes and contains the activities of 2-enoyl-CoA hydratase ( EC 4.2.1.17), L-3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) and 3-hy droxyacyl-CoA epimerase.