The interaction processes spectral study of tetraiodide meso-tetra(N-methyl-3-pyridyl)porphyrin with blood serum albumin has been carried out. The results obtained are considered in comparison with similar data for tetraphenylporphyrin and tetraiodide meso-tetra(N-methyl-4-pyridyl)porphyrin. It is established that interaction of albumin with the porphyrins under study leads to a change in the secondary structure of the protein accompanied by a decrease in the proportion of disordered fragments of the protein and an increase in β-structuring within the complexes. NCH3+ group isomerism position in the porphyrin compound significantly affects binding to albumin. Adding of the substituent in meta-position of the phenyl ring contributes to the increased affinity of protein to the cationic porphyrin, compared to the pair-substituted counterpart.
