Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (08): 887-891.doi: 10.3866/PKU.WHXB20040821

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Study on the Interaction Strength of La3+ or Eu3+ with Microperoxidase-8

Chen Ting-Ting;Huang Xiao-Hua;Du Jiang-Yan;Feng Yu-Ying;Liu Chang-Peng;Xing Wei;Lu Tian-Hong   

  1. College of Chemistry and Environment Science, Nanjing Normal University, Nanjing 210097; Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022
  • Received:2004-01-19 Revised:2004-04-01 Published:2004-08-15
  • Contact: Lu Tian-Hong

Abstract: The interaction of La3+ or Eu3+ with MP-8 was studied and the interaction strength of La3+ or Eu3+ with MP-8 was compared. Comparing with the UV-Vis absorption spectrum of the MP-8 solution without La3+ or Eu3+,the position of the Soret band for the MP-8 solution with La3+ or Eu3+ shifts to the red direction and the absorbance decreases. The extents of the red shift of the band position and the decrease in the absorbance for Eu3+ in the solutions without or with NaCl are larger than that for La3+. In 0.10 mol•L-1 NaCl solution, La3+ or Eu3+ could completely coordinate with carboxylate oxygen of two propionic acid groups of the heme group in an MP-8 molecule when the molar ratio of La3+ or Eu3+ and MP-8 is 10 and 5, respectively. In addition, the cyclic voltammetric results showed that the redox peak area of Eu3+ decreased 20% after adding MP-8 into the solution. These results clearly illustrated that one La3+ or Eu3+ ion would coordinate strongly with carboxylate oxygen of two propionic acid groups of the heme group in an MP-8 molecule and the excessive La3+ or Eu3+ ions weakly interact with the carboxylate oxygen in the peptide chain. The interaction between Eu3+ and MP-8 is stronger than that between La3+ and MP-8.

Key words: Microperoxidase-8(MP-8), La3+, Eu3+, UV-Vis absorption spectroscopy, Electrochemistry