Rational Redesign of Monoamine Oxidase A into a Dehydrogenase to Probe ROS in Cardiac Aging Luca Giacinto Iacovino Nicola Manzella Jessica Resta Maria Antonietta Vanoni Laura Rotilio Leonardo Pisani Dale Edward Edmondson Angelo Parini Andrea Mattevi Jeanne Mialet-Perez Claudia Binda 10.1021/acschembio.0c00366.s001 https://acs.figshare.com/articles/journal_contribution/Rational_Redesign_of_Monoamine_Oxidase_a_into_a_Dehydrogenase_to_Probe_ROS_in_Cardiac_Aging/12588168 Cardiac senescence is a typical chronic frailty condition in the elderly population, and cellular aging is often associated with oxidative stress. The mitochondrial-membrane flavoenzyme monoamine oxidase A (MAO A) catalyzes the oxidative deamination of neurotransmitters, and its expression increases in aged hearts. We produced recombinant human MAO A variants at Lys305 that play a key role in O<sub>2</sub> reactivity leading to H<sub>2</sub>O<sub>2</sub> production. The K305Q variant is as active as the wild-type enzyme, whereas K305M and K305S have 200-fold and 100-fold lower <i>k</i><sub>cat</sub> values and similar <i>K</i><sub>m</sub>. Under anaerobic conditions, K305M MAO A was normally reduced by substrate, whereas reoxidation by O<sub>2</sub> was much slower but could be accomplished by quinone electron acceptors. When overexpressed in cardiomyoblasts by adenoviral vectors, the K305M variant showed enzymatic turnover similar to that of the wild-type but displayed decreased ROS levels and senescence markers. These results might translate into pharmacological treatments as MAO inhibitors may attenuate cardiomyocytes aging. 2020-07-01 20:12:06 O 2 reactivity K 305S adenoviral vectors K 305M Rational Redesign oxidative deamination attenuate cardiomyocytes mitochondrial-membrane flavoenzyme ... wild-type enzyme ROS levels Lys 305 k cat values Monoamine Oxidase frailty condition expression increases K 305Q variant quinone electron acceptors K m Probe ROS O 2 Cardiac Aging Cardiac senescence H 2 O 2 production oxidative stress K 305M MAO senescence markers K 305M variant MAO inhibitors