title: Capillary electrophoresis of r-hirudin and a polyethylene glycol derivative of r-hirudin (PEG-hirudin).
abstract: Recombinant (r-) hirudins and PEG-hirudin are currently tested for anticoagulant therapy. For their concentration measurement, radioimmunoassay and HPLC methods are available. The separation of r- and PEG-hirudin is currently performed by HPLC. However, the sensitivity of the method is low. Capillary electrophoresis is a rapid, selective technique that requires low sample amounts. Our aim was the development of a capillary electrophoresis method to measure r- and PEG-hirudin. The results are as follows: In a borate solution (0.3% boric acid and 0.4% sodium tetraborate, pH 9.5) r-hirudin was separated from PEG-hirudin in a purified system using a fused silica capillary (50 cm long and 75-micron i.d. and reversed polarity). A neutral capillary with a 20 mM tricine buffer (pH 8.0, field strength 500 V/cm) was also effective in resolving r- from PEG-hirudin. A linear correlation was found between the peak area and the concentration between 20 micrograms/mL and 10 mg/mL for hirudin (r2 = 0.99) and between 1.25 and 10 mg/mL for PEG-hirudin (r2 = 0.99). In human plasma mixtures, r- and PEG-hirudin were completely separated. The linear correlation between the peak area and the concentration was r2 = 0.99.
  
  
  CONCLUSIONS
  In a fused silica capillary, r- and PEG-hirudin are separated in a purified system. Capillary electrophoresis which is performed in a neutral capillary, resolves r- from PEG-hirudin in a purified system, in plasma and in urine. The sensitivities of the methods are comparable. Capillary electrophoresis separates r- from PEG-hirudin and may be applied to biologic systems to measure the concentration and purity of r- and PEG-hirudin.
authors.affiliation: 1st Department of Medicine, Faculty of Clinical Medicine Mannheim, University of Heidelberg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Malsch
authors.forename: A
authors.initials: A
authors.lastname: Timmermann
authors.forename: J
authors.initials: J
authors.lastname: Harenberg
mesh_terms: D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D006629:Hirudins / Q000031:analogs & derivatives* / Q000032:analysis*; D006801:Humans; D011994:Recombinant Proteins / Q000032:analysis
chemical_list: D006629:Hirudins; D011994:Recombinant Proteins; C104614:polyethyleneglycol-hirudin