Coordination Chemistry of Nitric Oxide and Biological Signaling

OLABE, JOSÉ

Science Reviews - from the end of the world

Centro de Estudios sobre Ciencia, Desarrollo y Educación Superior

Lugar: Ciudad Autónoma de Buenos Aires; Año: 2020 vol. 2 p. 64 - 99

Nitric Oxide (NO) is a key intermediate in the nitrogen redox cyclesthat operate in soils, water and biological fluids, affording reversibleinterconversions between nitrates to ammonia and vice-versa. Thediscovery of its biosynthesis in mammals for signaling purposesgenerated a research explosion on the ongoing chemistry occurringin specific cellular compartments, centered on NO reactivity towardO2, thiols, amines, and transition metals, as well as derivativesthereof. The present review deals with the coordination chemistry ofNO toward selected iron and ruthenium centers. We place specificattention to the three redox states of the nitrosyl group: NO+, NOand NO?/HNO, describing changes in structure and reactivity as coordination takes place. Noteworthy arethe results with the most reduced nitroxyl-species that allow establishing the changes in the measurablepKa values for the HNO-bound complexes, also revealing the abrupt decrease in reducing power andtrans-releasing abilities of the protonated species over the unprotonated ones, NO?. Comparative resultsusing non-heme and heme proteins and models prove useful for suggesting further improvements in thecurrent research status of complex enzymatic behavior.Keywords:nitric oxide, nitroxyl, nitrous oxide, nucleophilic/electrophilic addition, disproportionation, nitrosation,dioxygenation, hydrogen sulfide, thionitrous acid, thionitrites, perthionitrites