title: Prussian Blue acts as a mediator in a reagentless cytokinin biosensor.
abstract: An electrochemical biosensor for detection of the plant hormone cytokinin is introduced. Cytokinin homeostasis in tissues of many lower and higher plants is controlled largely by the activity of cytokinin dehydrogenase (CKX, EC 1.5.99.12) that catalyzes an irreversible cleavage of N(6)-side chain of cytokinins. Expression of Arabidopsis thaliana CKX2 from Pichia pastoris was used to prepare purified AtCKX2 as the basis of the cytokinin biosensor. Prussian Blue (PrB) was electrodeposited on Pt microelectrodes prior to deposition of the enzyme in a sol-gel matrix. The biosensor gave amperometric responses to several cytokinins. These responses depended on the presence of both the enzyme and the Prussian Blue. Thus Prussian Blue must act as an electron mediator between the FAD centre in CKX2 and the Pt surface.
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 813/21, 783 71 Olomouc, Czech Republic. marta.kowalska@email.cz
authors.forename: Marta
authors.initials: M
authors.lastname: Kowalska
authors.forename: Faming
authors.initials: F
authors.lastname: Tian
authors.forename: Mária
authors.initials: M
authors.lastname: Šmehilová
authors.forename: Petr
authors.initials: P
authors.lastname: Galuszka
authors.forename: Ivo
authors.initials: I
authors.lastname: Frébort
authors.forename: Richard
authors.initials: R
authors.lastname: Napier
authors.forename: Nicholas
authors.initials: N
authors.lastname: Dale
mesh_terms: D017360:Arabidopsis / Q000201:enzymology; D015374:Biosensing Techniques / Q000379:methods*; D003583:Cytokinins / Q000032:analysis*; D055664:Electrochemical Techniques / Q000379:methods; D004595:Electroplating; D005295:Ferrocyanides / Q000737:chemistry*; D008839:Microelectrodes; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010843:Pichia / Q000378:metabolism; D010984:Platinum / Q000737:chemistry; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D003583:Cytokinins; D005295:Ferrocyanides; D011994:Recombinant Proteins; D010984:Platinum; D010088:Oxidoreductases; C019984:cytokinin oxidase; C000170:ferric ferrocyanide