Are there protective enzymatic pathways to regulate high local nitric oxide (•NO) concentrations in cells under stress conditions?

This paper examines, from a chemical perspective, the hypothesis of the existence of protective enzymes whose role would be to regulate the high local nitric oxide ((-)NO) concentrations that are released in (-)NO-generating cells in situations of response to oxidative stress. These enzymes should play the role, with respect to (-)NO, either of a reductase or of a dismutase. The energetics of the intervening transformations is herein presented, along with a review of pertinent literature. An attempt is made in order to describe the physiognomy of such enzymes, in relation with the literature data. Experimental investigation is needed to further evaluate the validity of such a hypothesis. (C) 2000 Societe francaise de biochimie et biologie moleculaire / Editions scientifiques et medicales Elsevier SAS.