title: Effect of Tris on catalytic activity of MP-11.
abstract: The effect of tris(hydroxymethyl)aminomethane (Tris) on the catalytic activity and microstructure of heme undecapeptide, microperoxidase-11 (MP-11) in the aqueous solution was investigated using cyclic voltammetry, circular dichroism (CD) spectroscopy, UV-vis absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found for the first time that Tris would inhibit the catalytic activity and electrochemical reaction of MP-11 at the glassy carbon (GC) electrode. This is mainly due to the fact that Tris would induce more alpha-helix and beta-turn conformations from the random coil conformation of MP-11, cause the asymmetric split-up in the Soret band region of MP-11, increase the non-planarity of the heme of MP-11, and change the electron densities of N, O and S atoms of MP-11. Meanwhile, It was found that the electrochemical reaction of MP-11 with Tris at GC electrode is diffusion-controlled, and the diffusion coefficient of MP-11 and the rate constant for the heterogeneous electron transfer of MP-11 in the presence of Tris are decreased by 19% and 16%, respectively. Further experiments showed that the electrocatalytic current of MP-11 on the reduction of H2O2 is decreased by about 25% after the addition of Tris to the MP-11 solution.
authors.affiliation: Department of Chemistry, Nanjing Normal University, Nanjing 210097, People's Republic of China.
authors.forename: Zhaopeng
authors.initials: Z
authors.lastname: Qi
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: Dongmei
authors.initials: D
authors.lastname: Sun
authors.forename: Cun
authors.initials: C
authors.lastname: Li
authors.forename: Tianhong
authors.initials: T
authors.lastname: Lu
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Ding
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Huang
mesh_terms: D002384:Catalysis / Q000187:drug effects; D004563:Electrochemistry; D004566:Electrodes; D010544:Peroxidases / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary; D013057:Spectrum Analysis; D014325:Tromethamine / Q000494:pharmacology*
chemical_list: D014325:Tromethamine; D010544:Peroxidases; C021799:microperoxidase