• Discontinuous and continuous separation of the monomeric and dimeric forms of human bone morphogenetic protein-2 from renaturation batches.

      Gueorguieva, Ludmila; Vallejo, Luis Felipe; Rinas, Ursula; Seidel-Morgenstern, Andreas; Otto-von-Guericke-Universität Magdeburg, Institut für Verfahrenstechnik, PO Box 4120, D-39106 Magdeburg, Germany. (2006-12-01)
      Bone morphogenetic protein-2 (BMP-2) is one of the most interesting of the approximately 14 BMPs which belong to the transforming-growth-factor-beta (TGF-beta) superfamily. BMP-2 induces bone formation and thus plays an important role as a pharmaceutical protein. Recently, rhBMP-2 has been produced in form of inactive inclusion bodies in Escherichia coli. After solubilization and renaturation the biologically active dimeric form of rhBMP-2 can be generated. However, inactive monomers of BMP-2 are also formed during the renaturation process which must be separated from the active dimeric BMP-2. The purpose of this paper is to present: (a) results of an experimental study of a chromatographic separation of the monomeric and dimeric forms; and (b) a concept for a continuous counter-current simulated moving bed (SMB) process. The capacity of heparin as stationary phase was estimated for different salt concentrations in the mobile phase. A simulation study of a three-zone SMB process was performed applying a two step salt gradient. The results reveal the potential of the process for the purification of the dimeric BMP-2.
    • Isolation of isomangiferin from honeybush (Cyclopia subternata) using high-speed counter-current chromatography and high-performance liquid chromatography.

      de Beer, Dalene; Jerz, Gerold; Joubert, Elizabeth; Wray, Victor; Winterhalter, Peter; ARC Infruitec-Nietvoorbij, Stellenbosch, South Africa. dbeerd@arc.agric.za (2009-05-08)
      Isomangiferin was isolated from Cyclopia subternata using a multi-step process including extraction, liquid-liquid partitioning, high-speed counter-current chromatography (HSCCC) and semi-preparative reversed-phase high-performance liquid chromatography (HPLC). Enrichment of phenolic compounds in a methanol extract of C. subternata leaves was conducted using liquid-liquid partitioning with ethyl acetate-methanol-water (1:1:2, v/v). The enriched fraction was further fractionated using HSCCC with a ternary solvent system consisting of tert-butyl methyl ether-n-butanol-acetonitrile-water (3:1:1:5, v/v). Isomangiferin was isolated by semi-preparative reversed-phase HPLC from a fraction containing mostly mangiferin and isomangiferin. The chemical structure of isomangiferin was confirmed by LC-high-resolution electrospray ionization MS, as well as one- and two-dimensional NMR spectroscopy.