title: Influence of Cu(II) on the interaction between sulfite and horseradish peroxidase in vitro.
abstract: This paper discussed the quantitative influence of Cu(II) on the interaction between horseradish peroxidase (HRP) and sulfite (SO3(2-)), which is a derivate of sulfite dioxide in human bodies, by using fluorescence spectrum and ultraviolet (UV) absorption spectrometry in vitro. The results show that under the conditions of physiological pH and room-temperature, Cu(II) can bind strongly with both the protein part and the ferroporphyrin part in HRP at a low concentration (10(-4) mol L(-1)), and the combination constants are 2.047 x 10(3) and 7.66 x 10(2) L mol(-1), respectively. Under the same conditions, SO3(2-) at low concentrations (<0.15 mol L(-1)) has little quenching for the fluorescence of HRP at 330 nm, and the combination constant is 0.108 L mol(-1). While the fluorescence intensity at 440 nm enhance gradually with the increased concentration of SO3(2-) (<0.1 mol L(-1)), and the combination constant is 8.219 L mol(-1). These indicate that SO3(2-) at low concentration has little reaction with the enzyme protein part in HRP but obvious reaction with the ferroporphyrin part in HRP. After SO3(2-) at low concentrations is added into the HRP-Cu(II) binary system, the reaction constants between SO3(2-) and the enzyme protein part in HRP increase rapidly. Compared with the absence of Cu(II), the combination constant of SO3(2-) with the enzyme protein part in HRP increases nearly 70 times with a certain Cu(II) concentration (5.0 x 10(-4) mol L(-1)) in the system. However, the presence of Cu(II) in the system has little effect on the reaction constants between SO3(2-) and the ferroporphyrin part in HRP.
authors.affiliation: College of Environment and Resources, Shanxi University, Taiyuan 030006, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Lan
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Guo
authors.forename: Xiao-Ying
authors.initials: XY
authors.lastname: Yuan
mesh_terms: D003300:Copper / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013447:Sulfites / Q000737:chemistry*; D013458:Sulfur Dioxide / Q000737:chemistry*
chemical_list: D013447:Sulfites; D013458:Sulfur Dioxide; D003300:Copper; D006735:Horseradish Peroxidase