title: One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III).
abstract: One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III) was investigated using some biophysical and biochemical methods. Firstly, it was found that a large amount of Tb(III) can be distributed on the cell wall, that some Tb(III) can enter into the horseradish cell, indicating that peroxidase was mainly distributed on cell wall, and thus that Tb(III) would interact with horseradish peroxidase (HRP) in the plant. In addition, peroxidase bioactivity was decreased in the presence of Tb(III). Secondly, a new peroxidase-containing Tb(III) complex (Tb-HRP) was obtained from horseradish after treatment with Tb(III); the molecular mass of Tb-HRP is near 44 kDa and the pI is about 8.80. Thirdly, the electrocatalytic activity of Tb-HRP is much lower than that of HRP obtained from horseradish without treatment with Tb(III). The decrease in the activity of Tb-HRP is due to the destruction (unfolding) of the conformation in Tb-HRP. The planarity of the heme active center in the Tb-HRP molecule was increased and the extent of exposure of Fe(III) in heme was decreased, leading to inhibition of the electron transfer. The microstructure change in Tb-HRP might be the result of the inhibition effect of Tb(III) on peroxidase activity in horseradish.
authors.affiliation: Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing 210097, People's Republic of China.
authors.forename: Shaofen
authors.initials: S
authors.lastname: Guo
authors.forename: Rui
authors.initials: R
authors.lastname: Cao
authors.forename: Aihua
authors.initials: A
authors.lastname: Lu
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhou
authors.forename: Tianhong
authors.initials: T
authors.lastname: Lu
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Ding
authors.forename: Chaojun
authors.initials: C
authors.lastname: Li
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Huang
mesh_terms: D031215:Armoracia / Q000187:drug effects* / Q000201:enzymology* / Q000648:ultrastructure; D002460:Cell Line; D002942:Circular Dichroism; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D006735:Horseradish Peroxidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D013058:Mass Spectrometry; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D013725:Terbium / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D013725:Terbium; D006735:Horseradish Peroxidase