Spectral Studies on the Interaction between Mercuric Ion and ApoCopC

Abstract

Abstract The interaction between mercuric ion and apoCopC in the absence or presence of cupric ion was investigated through difference UV spectra in Hepes buffer (10 mmol·L −1 ) at pH 7.4. The results suggest that mercuric ion can bind to C ‐ and N ‐terminal binding sites of apoCopC, and the conditional binding constants were calculated to be k N =(6.79±1.12)×10 6 mol −1 ·L and k C =(3.06±0.05)×10 5 mol −1 ·L. Using urea as a chemical agent, the conformational stabilities of apoCopC and Hg 2+ N ‐CopC‐Hg 2+ C were monitored by fluorescence spectrum in Hepes buffer (50 mmol·L −1 ) at pH 7.4. The free energy of stabilization is (14.69±0.85) and (16.66±0.55) kJ·mol −1 , respectively. Hg 2+ N ‐CopC‐Hg 2+ C is more stable than apoCopC.