The interaction of Methylthymol Blue(MTB)-Zinc! compound and Alizarin Red S(ARS)-Aluminum" compound with Bovine serum albumin (BSA) was investigated by UV-Vis spectrophotometric method in acidic buffer solution. MTB-Zn!-BSA was a blue color compound, which possesses maximum absorption at 613 nm with 172 nm, 174 nm and 18 nm of red shift compared to the MTB, MTB-BSA and MTB-Zn! complexes respectively. Dual wavelength substantial amount ratio method, balance dialysis substantial amount ratio method and unity wavelength substantial amount ratio method were compared. The following results were obtained: the apparent molar absorptivity of MTB-Zn! with BSA was ε=2.20×104 L·mol-1·cm-1. Conditional proportion were defined, nMTB∶nZn!∶nBSA=2∶2∶1; condition combination constant, K=2.07×1010. Combination proportion were defined, nARS∶nAl"∶ nBSA=6∶4∶1. Condition equilibrium constant of reaction of ARS-Al" with BSA was K=8.80×108. The apparent mo- lar absorptivity of ε=2.65×104 L·mol-·1cm-1. It is suggested that combination between BSA and MTB-Zn" is due to coordination force. That combination between BSA and ARS-Al" is due to the coordination bond and electro- static force.
The interaction between Sm(Ⅲ)(MTB)2 complex and Herring Sperm DNA has been studied by UV-Vis spectral, Fluorescence spectral in buffer solution of Tris-HCl (pH=7.25) using Neutral Red (NR) as a probe. The intercalation and electrostatic manner are confirmed to be the two major modes for interaction between Sm(Ⅲ)(MTB)2 complex and Herring Sperm DNA. The balance constant of Sm(Ⅲ)(MTB)2 rare earth metal complex and Herring Sperm DNA is K=4.10 × 104 L·mol-1. The results indicate that biological functions of Herring Sperm DNA are changed to a certain extend due to the interaction between Sm(Ⅲ)(MTB)2 rare earth metal complex and Herring Sperm DNA.
