Effect of Cationic and Anionic Porphyrins on the Structure and Activity of Adenosine Deaminase

摘要

Kinetic and structural studies have been carried out on the effects of meso-tetrakis(4-sulfonatophenyl)-porphyrin (H2TPPS4) as an anionic and meso-tetrakis(3-N-methyl-pyridyl)porphyrin (H2TMPYP) as a cationic porphyrin with adenosine deaminase (ADA) in 25 mM citrate/phosphate buffer, pH = 4-8, at 37 °C using UV-vis spectrophotometry, circular dichroism (CD), fluorescence spectrophotometry as well as molecular dynamics (MD) and molecular docking. Kinetic results showed that the two porphyrins are non-competitive inhibitors. Increasing pH, increases K1 and cationic porphyrin has a higher K1 and lower binding constant (K_b) at all pH ranges. Analyzing the secondary structure revealed that both ligands decrease the secondary structure and that the anionic porphyrin is more effective.