How to Find an HNO Needle in a (Bio)-Chemical Haystack

Abstract

Azanone (also called nitroxyl or simply HNO) is a highly reactive compound with very interesting chemical properties, and whose role in several chemical and biochemical reactions has not been completely elucidated to date. Its high reactivity, mainly toward itself, originates its intrinsic elusive nature. Nitroxyl dimerizes at a very fast rate, which is second order in its concentration. Thus its maximum concentration and lifetime are severely limited. Azanone also reacts fast with its sibling NO, and at a moderate rate with oxygen (1). Thus, its reactivity is mostly studied in an anaerobic environment. As in the case of NO, the biological targets, of HNO have been shown to be mainly thiols (1, 2), and metalloproteins, especially heme proteins (3?7). As shown later, these reactions are fast and thus can compete with dimerization, allowing their use as trapping agents.