›› 2005, Vol. 48 ›› Issue (2): 290-294.doi:

• RESEARCH PAPERS • Previous Articles     Next Articles

Inhibitory effect of cupferron on the activity of polyphenoloxidase from Pieris rapae(L.) (Lepidoptera: Pieridae)

XUE Chao-Bin1, WANG Qin2, KE Li-Na2, CHEN Qing-Xi2, LUO Wan-Chun1*   

  1. College of Plant Protection, Shandong Agricultural University
  • Online:2005-07-10 Published:2005-11-20
  • Contact: LUO Wan-Chun

Abstract: The kinetic properties of polyphenoloxidase (PPO) from Pieris rapae (L.) were studied after the enzyme was partially purified by 35% saturated (NH4)2SO4 and chromatographed on a Sephadex G-100 gel filtration. Meanwhile, the effects of PPO on the oxidation of L-DOPA by adding copper ion or cupferron were also studied. The results showed that the activity of PPO was enhanced by Cu2+ in the concentration of 0-0.100 mmol/L; however, the activity was inhibited by the same ion when the concentration was over 0.125 mmol/L, and the IC50 was estimated to be 0.651±0.022 mmol/L. The results also indicated that the reaction of cupferron with the PPO is a reversible course with remaining enzyme activity, the inhibitory mechanism belongs to be the competitive type and the IC50 was estimated to be 0.100±0.012 mmol/L. Furthermore, the equilibrium constant for cupferron was determined to be 0.076±0.013 mmol/L. 

Key words: Pieris rapae, polyphenoloxidase, copper ion, cupferron, inhibition