Diphenylene iodonium (DPI) is known for its inhibitory activities against many flavin- and heme-dependent enzymes, and is often used as an NADPH oxidase inhibitor. We probed the efficacy of DPI on two well-known drug targets, the human monoamine oxidases MAO A and B. UV-visible spectrophotometry and steady-state kinetics experiments demonstrate that DPI acts as a competitive and reversible MAO inhibitor with Ki values of 1.7 and 0.3 μM for MAO A and MAO B, respectively. Elucidation of the crystal structure of human MAO B bound to the inhibitor revealed that DPI binds deeply in the active-site cavity to establish multiple hydrophobic interactions with the surrounding side chains and the flavin. These data prove that DPI is a genuine MAO inhibitor and that the inhibition mechanism does not involve a reaction with the reduced flavin. This binding and inhibitory activity against the MAOs, two major reactive oxygen species (ROS)-producing enzymes, will have to be carefully considered when interpreting experiments that rely on DPI for target validation and chemical biology studies on ROS functions.
Diphenylene Iodonium Is a Noncovalent MAO Inhibitor: A Biochemical and Structural Analysis / Iacovino, L. G.; Reis, J.; Mai, A.; Binda, C.; Mattevi, A.. - In: CHEMMEDCHEM. - ISSN 1860-7179. - 15:15(2020), pp. 1394-1397. [10.1002/cmdc.202000264]
Diphenylene Iodonium Is a Noncovalent MAO Inhibitor: A Biochemical and Structural Analysis
Mai A.;
2020
Abstract
Diphenylene iodonium (DPI) is known for its inhibitory activities against many flavin- and heme-dependent enzymes, and is often used as an NADPH oxidase inhibitor. We probed the efficacy of DPI on two well-known drug targets, the human monoamine oxidases MAO A and B. UV-visible spectrophotometry and steady-state kinetics experiments demonstrate that DPI acts as a competitive and reversible MAO inhibitor with Ki values of 1.7 and 0.3 μM for MAO A and MAO B, respectively. Elucidation of the crystal structure of human MAO B bound to the inhibitor revealed that DPI binds deeply in the active-site cavity to establish multiple hydrophobic interactions with the surrounding side chains and the flavin. These data prove that DPI is a genuine MAO inhibitor and that the inhibition mechanism does not involve a reaction with the reduced flavin. This binding and inhibitory activity against the MAOs, two major reactive oxygen species (ROS)-producing enzymes, will have to be carefully considered when interpreting experiments that rely on DPI for target validation and chemical biology studies on ROS functions.File | Dimensione | Formato | |
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