N-alpha-Acetyl-L-arginine, also known as N-alpha-acetylarginine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylarginine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylarginine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-arginine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618).  About 85% of all human proteins and 68% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT‚Äôs (PMID: 30054468).  These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid.  N-acetylated amino acids, such as N-acetylarginine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free arginine can also occur. Many N-acetylamino acids, including N-acetylarginine are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759; PMID: 7777105). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557). N-alpha-Acetyl-L-arginine serum levels (and other guanidino compounds) were elevated of all the hyperargininemic patients are higher than the normal range. Untreated hyperargininemic patients have the highest guanidino compound levels in cerebrospinal fluid. N-alpha-Acetyl-L-arginine is also increased in the urine or hyperargininemic patients. N-alpha-Acetyl-L-arginine is one of the guanidino compounds found elevated in the serum of hemodialyzed renal insufficient (uremic) pediatric patients.