Sialic Acid Aldolase
Source Recombinant E. Coli K1 clone
60 µl aliquot of enzyme (6 U) in 20 mM tris-HCl, pH 7.5
Specific Activity 15 U/mg
Activity 100 U/ml
Molecular weight ~32,000 daltons
Sialic Acid Aldolase (N-Acetylneuraminate pyruvate lyase, EC 18.104.22.168) catalyzes the reversible reaction of sialic acid (N-acetylneuraminic acid) to N-acetylmannosamine and pyruvic acid.
The enzyme is found in several bacterial strains which use the reverse reaction to degrade N-acetylneuraminic acid (sialic acid).The forward reaction is particularly useful for the determination of sialic acid concentrations by quantitatively converting it to N-acetylmannosamine and pyruvate.
Since sialic acid is both negatively charged and a non-reducing sugar, its direct analysis is more difficult than conventional sugars. N-acetylmannosamine, however, can be assayed as a conventional reducing sugar by various techniques such as flourescent dye or radioactive labeling.
Alternatively, the pyruvic acid generated in the reaction can be assayed using enzymes such as Lactic Dehydrogenase, coupled to NADH oxidation, to reduce pyruvate. NADH oxidation can be spectrophotometrically quantitated. Another method uses pyruvate oxidase to generate hydrogen peroxide which is measured colorimetrically.
In addition to free neuraminic acid, N-acetylneuraminic Acid Aldolase can be used to determine the total amount of neuraminic acid in:
by first digesting the whole cells, glycoprotein or polysaccharide with QA-Bio Sialidase Au (E-S001), and then determining total N-acetylneuraminic acid
Kolisis, F.N. An immobilized bienzyme system for assay of sialic acid. Biotechnol Appl Biochem 8:).
Simpson, H., G. D. Ghusney, M. A. Crook and J. C. Pickup. Serum sialic acid enzymatic assay based on microtitre plates: application for measuring capillary serum sialic acid concentrations. Br J Biomed Sci 50:164-167 (1993).
Sugahara K, K. Sugimoto, O. Nomura and T. Usui. Enzymatic assay of serum sialic acid. Clin Chim Acta 108:).
Lilley, G.G., M. von Itzstein and N. Ivancic. High-Level Production and Purification of Escherichia coli N-Acetylneuraminic Acid Aldolase (EC 22.214.171.124) Protein Expression and Purification 3:434-440 (1992).
Ohta,Y., K. Watanabe and A. Kimura. Complete Sequence of E. coli N-acetylneuraminate lyase. Nucleic Acids Res.13:8843-8852(1985).