Publications

• Configuration of substrate and products of N-acetylneuraminate pyruvate-lyase from Clostridium perfringens.

  Deijl C.M., Vliegenthart J.F.

  To characterize the true substrate for aldolase from Clostridium perfringens (optimum pH = 7.2) several experiments were carried out wherein the substrate Neu5Ac was generated in situ at pH 5.4 by the action of sialidase on its substrate Neu5Ac(alpha, 2 leads to 3) lactose. The alpha-anomer formed ... >> More

  To characterize the true substrate for aldolase from Clostridium perfringens (optimum pH = 7.2) several experiments were carried out wherein the substrate Neu5Ac was generated in situ at pH 5.4 by the action of sialidase on its substrate Neu5Ac(alpha, 2 leads to 3) lactose. The alpha-anomer formed in this reaction was found to be split by aldolase at this pH into ManNAc and pyruvate. beta-Neu5Ac as such was not converted at pH 5.4. However, when it was first mutarotated until the equilibrium mixture alpha:beta = 7.2:92.8 was obtained, it could be split. Inhibition experiments suggested that Neu5Ac was bound to the enzyme in a conformation that strongly resembled that of its alpha-anomer. The open chain form of ManNAc which arose after the action of aldolase preferentially formed the alpha-anomer followed by a fast mutarotation. << Less

  Biochem Biophys Res Commun 111:668-674(1983) [PubMed] [EuropePMC]

• The metalloprotein YhcH is an anomerase providing N-acetylneuraminate aldolase with the open form of its substrate.

  Kentache T., Thabault L., Deumer G., Haufroid V., Frederick R., Linster C.L., Peracchi A., Veiga-da-Cunha M., Bommer G.T., Van Schaftingen E.

  N-acetylneuraminate (Neu5Ac), an abundant sugar present in glycans in vertebrates and some bacteria, can be used as an energy source by several prokaryotes, including Escherichia coli. In solution, more than 99% of Neu5Ac is in cyclic form (≈92% beta-anomer and ≈7% alpha-anomer), whereas <0.5% is ... >> More

  N-acetylneuraminate (Neu5Ac), an abundant sugar present in glycans in vertebrates and some bacteria, can be used as an energy source by several prokaryotes, including Escherichia coli. In solution, more than 99% of Neu5Ac is in cyclic form (≈92% beta-anomer and ≈7% alpha-anomer), whereas <0.5% is in the open form. The aldolase that initiates Neu5Ac metabolism in E. coli, NanA, has been reported to act on the alpha-anomer. Surprisingly, when we performed this reaction at pH 6 to minimize spontaneous anomerization, we found NanA and its human homolog NPL preferentially metabolize the open form of this substrate. We tested whether the E. coli Neu5Ac anomerase NanM could promote turnover, finding it stimulated the utilization of both beta and alpha-anomers by NanA in vitro. However, NanM is localized in the periplasmic space and cannot facilitate Neu5Ac metabolism by NanA in the cytoplasm in vivo. We discovered that YhcH, a cytoplasmic protein encoded by many Neu5Ac catabolic operons and belonging to a protein family of unknown function (DUF386), also facilitated Neu5Ac utilization by NanA and NPL and displayed Neu5Ac anomerase activity in vitro. YhcH contains Zn, and its accelerating effect on the aldolase reaction was inhibited by metal chelators. Remarkably, several transition metals accelerated Neu5Ac anomerization in the absence of enzyme. Experiments with E. coli mutants indicated that YhcH expression provides a selective advantage for growth on Neu5Ac. In conclusion, YhcH plays the unprecedented role of providing an aldolase with the preferred unstable open form of its substrate. << Less

  J. Biol. Chem. 296:100699-100699(2021) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Chemistry, metabolism, and biological functions of sialic acids.

  Schauer R.

  Adv Carbohydr Chem Biochem 40:131-234(1982) [PubMed] [EuropePMC]

• The sialic acids. I. The structure and enzymatic synthesis of N-acetylneuraminic acid.

  COMB D.G., ROSEMAN S.

  J Biol Chem 235:2529-2537(1960) [PubMed] [EuropePMC]

• [Cleavage and synthesis of sialic acids with aldolase. NMR studies of stereochemistry, kinetics, and mechanisms].

  Baumann W., Freidenreich J., Weisshaar G., Brossmer R., Friebolin H.

  1H-NMR spectroscopy was used to study cleavage and synthesis of N-acetyl- and N-glycoloyl-D-neuraminic acid by Clostridium perfringens aldolase. Whereas the alpha-anomers of Neu5Ac and Neu5Gc serve as substrate in the cleavage reaction, alpha-ManNAc and alpha-ManNGc are its primary products. The s ... >> More

  1H-NMR spectroscopy was used to study cleavage and synthesis of N-acetyl- and N-glycoloyl-D-neuraminic acid by Clostridium perfringens aldolase. Whereas the alpha-anomers of Neu5Ac and Neu5Gc serve as substrate in the cleavage reaction, alpha-ManNAc and alpha-ManNGc are its primary products. The same alpha-anomers are needed by the aldolase for the synthesis of Neu5Ac and Neu5Gc. During the enzyme reaction in D2O both H-atoms at C-3 of Neu5Ac are exchanged by deuterium, H-3e reacting faster than H-3a. Rate constants and concentrations at equilibrium of reactants are temperature- and pH-dependent: The amount of Neu5Ac in equilibrium increases with decreasing temperature and increasing pH-value. Based on these results a mechanism of aldolase action is discussed. << Less

  Biol Chem Hoppe Seyler 370:141-149(1989) [PubMed] [EuropePMC]