title: Expression, purification and preliminary crystallization of amaranth 11S proglobulin seed storage protein from Amaranthus hypochondriacus L.
abstract: 11S globulin is one of the major seed storage proteins in amaranth. Recombinant protein was produced as up to approximately 80% of the total bacterial protein using Escherichia coli Rosetta-gami (DE3) containing pET21d with amaranth 11S globulin cDNA. The best expression condition was at 302 K for 20 h using LB medium containing 0.5 M NaCl. The recombinant protein was easily separated from most of the Escherichia coli proteins by precipitation with 0-40% ammonium sulfate solution. It formed aggregates at low temperature and at low salt concentrations. This behaviour may imply that it has a more hydrophobic nature than other 11S seed globulins. The crystals diffracted to 6 A resolution and belonged to space group P6(3), with unit-cell parameters a=b=97.6, c=74.8 A, gamma=120.0 degrees. One subunit of a trimer was estimated to be present in the asymmetric unit, assuming a Vsol of 41%. To obtain the complete structure solution, experiments to improve crystallization and flash-cooling conditions are in progress.
authors.affiliation: Laboratory of Food Quality Design and Development, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Mary Rose
authors.initials: MR
authors.lastname: Tandang-Silvas
authors.forename: Laura
authors.initials: L
authors.lastname: Carrazco-Peña
authors.forename: Ana Paulina
authors.initials: AP
authors.lastname: Barba de la Rosa
authors.forename: Juan Alberto
authors.initials: JA
authors.lastname: Osuna-Castro
authors.forename: Shigeru
authors.initials: S
authors.lastname: Utsumi
authors.forename: Bunzo
authors.initials: B
authors.lastname: Mikami
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Maruyama
mesh_terms: D027721:Amaranthus / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D015870:Gene Expression; D005916:Globulins / Q000737:chemistry* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D055314:Seed Storage Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D005916:Globulins; D010940:Plant Proteins; D055314:Seed Storage Proteins