Mitochondrial nitric oxide synthase

Nitric oxide (NO.) can bind to and inhibit the terminal enzyme of the mitochondrial respiratory chain, cytochrome c oxidase (complex IV). In vivo, NO. is made by the NO. synthase (NOS) family of enzymes, and considerable debate has recently arisen regarding a NOS inside mitochondria (termed 'mtNOS'). Such an enzyme is an intriguing proposition, since it affords unique organelle-based regulatory mechanisms for NO. synthesis, and has considerable implications for mitochondrial function. This review serves to discuss some of the current issues regarding mtNOS, such as its isoform identity, the availability of co-factors and substrates within the organelle, and potential physiological vs. pathological roles for the enzyme, all within the broader context of mitochondrial regulation by NO.. (C) 2004 Elsevier B.V. and Mitochondria Research Society. All rights reserved.