Homoarginine synthesis by rat kidney

Low Serum Homoarginine Is a Novel Risk Factor for Fatal Strokes in Patients Undergoing Coronary Angiography

“…[3][4][5][6] Interestingly, the key enzyme for homoarginine synthesis, arginine: glycine amidinotransferase, is upregulated in the failing heart and is highly expressed in the brain. 1,10 Inborn errors of this enzyme lead to disturbances in energy metabolism, so-called creatine deficiency syndromes, which are associated with mental disorders. 11 Our data are limited by the relatively low number of events, which preclude adequately powered analyses of specific causes of stroke deaths.…”

“…1 Previous studies suggest a role of homoarginine in the metabolism of the vasodilator nitric oxide. [2][3][4][5] Homoarginine has been shown to serve as a substrate for nitric oxide synthase and has been associated with endothelial function.…”

Serum L-Homoarginine Concentration is Elevated During Normal Pregnancy and is Related to Flow-Mediated Vasodilatation

“…33 Using an animal model, Ryan et al have shown that this enzyme can convert lysine to L-homoarginine in reactions analogous to those of the urea cycle (Fig 1) in which lysine replaces ornithine in the rat kidney. 34 Guanidinated amino acids, such as L-homoarginine, are also known to be more stable than lysine when incorporated into proteins. 35 One possibility with regard to guanidinated proteins is that the L-homoarginine is being transformed back to lysine by arginase in the liver and kidneys, 34 thus preventing lysine deficiency.…”

“…34 Guanidinated amino acids, such as L-homoarginine, are also known to be more stable than lysine when incorporated into proteins. 35 One possibility with regard to guanidinated proteins is that the L-homoarginine is being transformed back to lysine by arginase in the liver and kidneys, 34 thus preventing lysine deficiency. 36 It has been demonstrated that natural hormonal fluctuation during the menstrual cycle may reflect endothelial function, and FMD% has been shown to decrease in the early luteal phase compared with the follicular phase and increase again in the late luteal phase.…”

Citrullinemia: Enzymatic Evidence for Genetic Heterogeneity

“…These findings, taken in conjunction with the very low activities of the proposed steps of the "outer urea cycle" support the conclusion of Levin et al (9) that this is not likely to be a significant pathway for the formation of urea. Since lysine can be converted to homocitrulline and homoarginine in adult humans, the latter by a transamidination reaction in kidney (17), the increased excretion of homoarginine and homocitrulline may simply be secondary to the elevated lcvels of lysine in patient 3. Whether this elevation is caused by inhibition of normal lysine catabolism by citrulline (9).…”