title: Enhanced electron-transfer reactivity of horseradish peroxidase in phosphatidylcholine films and its catalysis to nitric oxide.
abstract: Direct electrochemistry of horseradish peroxidase (HRP) embedded in film of phosphatidylcholine (PC) is investigated at a pyrolytic graphite electrode by voltammetric methods. The electron-transfer reactivity between incorporated HRP and the electrode is found to be greatly enhanced by phosphatidylcholine film. Cyclic voltammetry (CV) of this incorporated peroxidase shows a pair of well-defined and nearly reversible peaks, and the cathodic and anodic peak potentials are located at about -0.261 and -0.180 V, respectively versus saturated calomel electrode at pH 5.5. Ultraviolet-visible absorption spectra indicate that the heme microenvironment of HRP in phosphatidylcholine film is similar to that of its native status. It is also observed that HRP modified electrode is able to catalyze the electrochemical reduction of nitric oxide. Experimental results reveal that the peak current related to nitric oxide reduction is linearly proportional to its concentration in the ranges of 2.0 x 10(-7) -5.0 x 10(-6) mol (-1) and 2.0 x 10(-5) -1.0 x 10(-4) mol(-1), based on which an unmediated biosensor for nitric oxide is developed.
authors.affiliation: Department of Biochemistry, National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, PR China.
authors.forename: Xinjian
authors.initials: X
authors.lastname: Liu
authors.forename: Wenjun
authors.initials: W
authors.lastname: Zhang
authors.forename: Yinxi
authors.initials: Y
authors.lastname: Huang
authors.forename: Genxi
authors.initials: G
authors.lastname: Li
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002384:Catalysis; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D004579:Electron Transport; D004800:Enzymes, Immobilized / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry*; D009569:Nitric Oxide / Q000032:analysis* / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D020099:Coated Materials, Biocompatible; D004800:Enzymes, Immobilized; D010713:Phosphatidylcholines; D009569:Nitric Oxide; D006735:Horseradish Peroxidase