Nacetylglutamat

N-acetylglutamate, also called N-acetyl-L-glutamate (NAG), is a derivative of the amino acid glutamate in which the amino group is acetylated. It occurs as an endogenous metabolite in humans and other animals and also serves as an intermediate in the arginine biosynthesis pathway of many bacteria and plants.

In humans and other vertebrates, N-acetylglutamate is produced in the mitochondria of the liver by the enzyme N-acetylglutamate synthase (NAGS) from glutamate and acetyl-CoA. Its principal biochemical role is as an essential allosteric activator of carbamoyl phosphate synthetase I (CPS1), the first enzyme of the urea cycle. NAG enables CPS1 to function efficiently, promoting conversion of ammonia to urea for excretion. Arginine positively regulates NAGS, so high arginine levels can increase NAG production and thereby upregulate CPS1 activity when nitrogen disposal is needed.

Defects in NAGS can impair CPS1 activation, leading to NAGS deficiency, a rare urea cycle disorder characterized by hyperammonemia. Therapy may involve the administration of carglumic acid (carbaglumic acid), a structural analog of N-acetylglutamate that directly activates CPS1, aiding ammonia detoxification. Dietary and medical management of urea cycle disorders may also be employed.

In many microorganisms and plants, N-acetylglutamate functions as an intermediate in arginine biosynthesis. There, it is formed by N-acetylglutamate synthase and proceeds through a dedicated pathway to produce arginine, with regulatory mechanisms that differ from the vertebrate urea cycle.

Chemical notes: N-acetylglutamate is the N-acetylamide of glutamic acid. It is primarily of physiological and metabolic interest rather than a dietary supplement.