title: Fructose-selective calorimetric biosensor in flow injection analysis.
abstract: A highly selective, interference free biosensor for the measurement of fructose in real syrup samples was developed. The assay is based on the phosphorylation of D(-)fructose to fructose-6-phosphate by hexokinase and subsequent conversion of fructose-6-phosphate to fructose-1,6-biphosphate by fructose-6-phosphate-kinase. The heat liberated in the second reaction is monitored using an enzyme thermistor. The major advantages of this biosensor are rapid and selective measurement of fructose without the need to eliminate glucose and inexpensive FIA-based, mediator-free calorimetric measurement suitable for regular fructose analysis. This method was optimised for parameters, such as pH, ionic strength, interference, operational stability and shelf life. Good and reproducible linearity (0.5-6.0 mM) with a detection limit of 0.12 mM was obtained. Fructose determination in commercial syrup samples and spiked samples confirmed the reliability of this set-up and technique. The biosensor gave reproducible results with good overall stability for continuous measurements over a period of three months besides a useful shelf life of six months. The method could be used for routine fructose monitoring in food samples.
authors.affiliation: Pure and Applied Biochemistry, Centre for Chemistry, Lund University, P.O Box 124, S-221 00 Lund, Sweden. sunil17_bhand@yahoo.com
authors.forename: Sunil G
authors.initials: SG
authors.lastname: Bhand
authors.forename: Srimathi
authors.initials: S
authors.lastname: Soundararajan
authors.forename: Ioana
authors.initials: I
authors.lastname: Surugiu-Wärnmark
authors.forename: Jaqueline Simona
authors.initials: JS
authors.lastname: Milea
authors.forename: Estera Szwajcer
authors.initials: ES
authors.lastname: Dey
authors.forename: Maria
authors.initials: M
authors.lastname: Yakovleva
authors.forename: Bengt
authors.initials: B
authors.lastname: Danielsson
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002151:Calorimetry / Q000379:methods*; D004800:Enzymes, Immobilized / Q000378:metabolism; D017022:Flow Injection Analysis / Q000379:methods*; D005504:Food Analysis; D005632:Fructose / Q000032:analysis*; D006597:Fructose-Bisphosphatase / Q000378:metabolism; D005636:Fructosephosphates / Q000737:chemistry; D006593:Hexokinase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D010766:Phosphorylation
chemical_list: D004800:Enzymes, Immobilized; D005636:Fructosephosphates; D005632:Fructose; C027618:fructose-6-phosphate; D006593:Hexokinase; D006597:Fructose-Bisphosphatase