Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (01): 213-216.doi: 10.3866/PKU.WHXB201228213

• PHOTOCHEMISTRY AND RADIATION CHEMISTRY • Previous Articles     Next Articles

Laser Flash Photolysis Study on Electron Transfer Oxidation Reaction of Tryptophan or Tyrosine with Triplet State Vitamin K3

TANG Rui-Zhi1,2, LI Hai-Xia1,2, LIU Yan-Cheng1,2, ZHANG Peng1,2, CAO Xi-Yan1,3, WANG Wen-Feng1   

  1. 1. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, P. R. China;
    2. Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. China;
    3. School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, Hunan Province, P. R. China
  • Received:2011-09-07 Revised:2011-10-25 Published:2011-12-29
  • Contact: WANG Wen-Feng
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21173252).

Abstract: Laser flash photolysis was used to study the photosensitized oxidation mechanism of vitamin K3, commonly known as 2-methyl-1,4-naphthoquinone (MQ), with tryptophan (TrpH) or tyrosine (TyrOH) in acetonitrile/water (1:1, V/V) solution. The triplet state of MQ reacted with TrpH or TyrOH by electron transfer with the formation of a MQ anion radical, which was directly observed in the transient absorption spectrum. The rate constants of the electron transfer reactions were determined to be 1.1×109 and 0.6×109 L·mol-1·s-1 for TrpH and TyrOH, respectively. The free energy changes (ΔG) of the reactions showed that the proposed electron transfer steps are thermodynamically feasible.

Key words: Vitamin K3, Tryptophan, Tyrosine, Laser flash photolysis