Complexes of bovine serum albumin with water-soluble Cu and Co containing cationic meso-tetra(4-N-oxyethylpyridyl)-porphyrins
Bovine serum albumin complexes with water-soluble cationic porphyrins, Cu - and Co-meso-tetra(4- N -hydroxyethylpyridyl)porphyrins ( CuT4OEPyP , CoT4OEPyP ), and their 3- N -analogs, meso-tetra(3- N -hydroxyethylpyridyl)porphyrins ( CuT3OEPyP , CoT3OEPyP ), have been investigated. The porphyrin-bovine serum albumin binding was monitored by the absorption in the visible region at 400-460 nm. The stoichiometry of binding and the binding constants of the porphyrins to bovine serum albumin were determined using binding isotherms and Scatchard plots. The K b values obtained for these porphyrin- bovine serum albumin complexes are 1.7 × 105 M −1, 3.2 × 105 M −1, 1.4 × 105 M −1 and 3 × 105 M −1 respectively. Binding constants are sensitive to pH and ionic strength of the solution.