Virtually all mammals produce two types: N-acetylneuraminic acid
(Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc).
Sialic acids are derived from neuraminic acid whose main derivative is N-acetylneuraminic acid
, which is generally used as a synonym for sialic acid (Ledeen and Yu 1976).
630] bearing the same biantennary carbohydrate structure composed of 2 N-acetylglucosamine (GlcNAc), 3 mannose (Man), 2 GlcNAc, 2 galactose (Gal), and 2 N-acetylneuraminic acid (NeuNAc; sialic acid; see structure in Table 2).
4) Nonstandard abbreviations: CACH, childhood-onset ataxia and central hypomyelination; VWM, vanishing white matter disease; CSF, cerebrospinal fluid; 2-DGE, 2-dimensional gel electrophoresis; MS, mass spectrometry; TFA, trifluoroacetic acid; MALDI, matrix-assisted laser desorption/ionization; MS/ MS, tandem mass spectrometry; FTMS, Fourier transform mass spectrometry; SORI, sustained off-resonance irradiation; CID, collision-induced dissociation; TOF, time-of-flight; GlcNAc, N-acetylglucosamine; Man, mannose; Gal, galactose; NeuNAc, N-acetylneuraminic acid (sialic acid); and Fuc, fucose.
An example is a concise synthesis of N-acetylneuraminic acid
(12) from N-acetylmannosamine (11) as outlined in Scheme 2.
Since many years, it is known that ML I binds to galactose, but current investigations propose a specific-binding site for ML I consisting of N-acetylglucosamin, galactose and terminal N-acetylneuraminic acid
3) Nonstandard abbreviations: SSD, sialic acid storage disease; ISSD, infantile sialic acid storage disease; NANA, N-acetylneuraminic acid
(free sialic acid); HPAE-PAD, high-performance anion-exchange pulsed amperometric detection; tMS, tandem mass spectrometry; KDN, 2-keto-3-deoxy-D-glycero-D-galactonononic acid; IS, internal standard; ESI, electrospray ionization; MRM, multiple reaction monitoring; ERNDIM, European Research Network for Evaluation and Improvement of Screening Diagnosis and Treatment of Inherited Disorders of Metabolism; and LOD, limit(s) of detection.
1) values for N-acetylneuraminic acid, N-aspartylglucosamine, N-acetylaspartic acid, and Man(1-4)G1cNAc, as representative N-acetylated compounds, were determined in urine of patients by the inversion-recovery technique.
Characteristically, a 20- to 200-fold increase in N-acetylneuraminic acid excretion in urine has been described in infantile cases of the disease.
Gal and N-acetylneuraminic acid
(NeuAc) are the only sugars implicated in the biosynthesis of both N-glycans and core 1 mucin type O-glycans; therefore, it is very likely that the genetic defect in patient B is situated in one of the three biosynthetic stages of one Gal or NeuAc.
Known concentrations of N-acetylneuraminic acid
were diluted in redistilled water.
The incremental residue masses for the commonly found residues are 162 amu for a hexose (Hex), 146 amu for a deoxyhexose (deoxyHex), 203 amu for an N-acetylhexosamine (HexNAc), and 291 amu for N-acetylneuraminic acid