R is for Arginine: Metabolism of Arginine Takes off Again, in New Directions
First published in 1962, Ray Bradbury's short story collection "R is for Rocket" provided a view of space travel with a prescience and sophistication that transformed the simpler notions of the time. And in a simpler era dating back only to the mid-1980s, L-arginine (abbreviated R in the single letter amino acid code) seemed to be just another amino acid, notable principally for its guanido group, which conferred arginine with a high pK and provided its distinction as one of the three basic amino acids. Abundant in many types of food, synthesized from simple precursors, or recycled in different tissues in the body, arginine is classified as a non-essential amino acid: except under extreme conditions, nutritional states of arginine deficiency are rare. Yet how much more complicated and interesting has arginine become in the past three decades! The role of arginine as a humdrum amino acid was forever transformed by the discovery that this amino acid is a substrate for the formation of nitric oxide by all mammalian nitric oxide synthases1,2. The metabolic transformations of arginine and their roles in cardiovascular (patho) physiology have since been explored in many hundreds of papers2-7. The current issue of Circulation reports a new and intriguing aspect of arginine metabolism involving the compound homoarginine8, with even broader implications for our understanding of the roles of metabolic systems in vascular biology and disease.
- Received August 26, 2013.
- Accepted August 26, 2013.