Background
What's New?
It was once thought
that the gas nitric oxide was simply an atmospheric pollutant Moncada
et. al (1993). However, relatively recent discoveries reveal that
cells synthesize nitric oxide and that NO is a critical physiological
signaling molecule. NO signaling is involved in numerous biological systems,
including the cardiovascular, pulmonary, and nervous systems Moncada
et. Al (1993).
In 1994, Cleeter et. Allearned that nitric oxide reversibly inhibits mitochondrial respiration by binding to the enzyme cytochrome c oxidase (CCO). This interaction with CCO implies that nitric oxide can play an important role in mitochondrial signaling.
Until recently, details of the molecular interaction of nitric oxide with cytochrome c oxidase were sketchy. Mason et. Al (2006) now propose a new mechanism for NO inhibition of CCO. The proposed mechanism accounts for NO's ability to regulate mitochondrial function throughout the wide range of normal physiological oxygen tensions and oxygen consumption rates.
To understand the interactions between NO and CCO, we will first examine each molecule individually. Let's begin by learning more about nitric oxide.