title: Characterization of a membrane-associated apoplastic lipoxygenase in Phaseolus vulgaris L.
abstract: An extracytoplasmic 86.7 kDa protein was isolated from intercellular washing fluids (IWF) of Phaseolus vulgaris etiolated hypocotyls. Micro sequencing of tryptic peptides of the 86.7 kDa protein revealed 100% identity with a bean lipoxygenase (LOX) protein fragment. Purified P87-LOX exhibited LOX activity characterized by an optimal pH of 6.0 and linolenic acid as an optimal substrate, and was classified as a 13-LOX with respect to its positional specificity of linoleic acid oxygenation. A protein identical to P87-LOX, as determined by MALDI-TOF analysis and biochemical characterization, was purified from hypocotyl microsomes. Immunoblot analysis showed that P87-LOX is present in plasma membrane-enriched fractions, from which it was solubilized using high ionic strength buffers. These observations suggest that P87-LOX is a peripheral protein associated to the apoplastic face of the plasma membrane.
authors.affiliation: Dipartimento di Biologia Vegetale, Università di Roma La Sapienza, Piazzale Aldo Moro 5, Roma 00185, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Sicilia
authors.forename: Benedetta
authors.initials: B
authors.lastname: Mattei
authors.forename: Felice
authors.initials: F
authors.lastname: Cervone
authors.forename: Daniela
authors.initials: D
authors.lastname: Bellincampi
authors.forename: Giulia
authors.initials: G
authors.lastname: De Lorenzo
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism; D008084:Lipoxygenase / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008861:Microsomes / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D027805:Phaseolus / Q000033:anatomy & histology* / Q000201:enzymology*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D008084:Lipoxygenase