title: Protein micelles from lipoxygenase 3.
abstract: Heat-induced conformational changes in lipoxygenase 3 were characterized by differential scanning calorimetry. The positions of the observed transitions were sensitive to the composition of the buffer. In particular, lipoxygenase 3 heated in carbonate buffer at pH 8.0 formed large soluble aggregates. Variable-temperature circular dichroism revealed that the formation of the aggregates was not accompanied by the unfolding of the C-terminal domain, which is composed primarily of alpha-helix. The aggregates were investigated using size exclusion chromatography, native polyacrylamide gel electrophoresis, dynamic light scattering, and electron microscopy. The data were consistent with the formation of roughly spherical particles with an average hydrodynamic radius of 26 nm and an approximate composite molecular weight of 10,000,000 Da. To account for the formation of soluble aggregates from lipoxygenase 3, we propose that hydrophobic amino acid residues are exposed by unfolding of the N-terminal beta-barrel domain of the protein resulting in the formation of protein micelles with a hydrophilic surface composed of the C-terminal domains.
authors.affiliation: Department of Chemistry, University of Toledo, Toledo, Ohio 43606, USA.
authors.forename: Pierre-Alexandre
authors.initials: PA
authors.lastname: Brault
authors.forename: Muhammed S T
authors.initials: MS
authors.lastname: Kariapper
authors.forename: Chau V
authors.initials: CV
authors.lastname: Pham
authors.forename: Robert A
authors.initials: RA
authors.lastname: Flowers
authors.forename: William T
authors.initials: WT
authors.lastname: Gunning
authors.forename: Priya
authors.initials: P
authors.lastname: Shah
authors.forename: Max O
authors.initials: MO
authors.lastname: Funk
mesh_terms: D002021:Buffers; D002152:Calorimetry, Differential Scanning; D002623:Chemistry Techniques, Analytical / Q000379:methods; D019281:Dimerization; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008084:Lipoxygenase / Q000737:chemistry*; D008823:Micelles; D008970:Molecular Weight; D010316:Particle Size; D010940:Plant Proteins / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012996:Solutions; D013025:Glycine max / Q000737:chemistry
chemical_list: D002021:Buffers; D008823:Micelles; D010940:Plant Proteins; D012996:Solutions; C095864:lipoxygenase 3; D008084:Lipoxygenase