Margret Wember

The nature of sialic acids in human lymphocytes

Analysis of the sialic acids obtained by mild acid hydrolysis of B lymphocytes reveals the presence of N-acetylneuraminic acid and 9-O-acetyl-N-acetylneuraminic acid. For T lymphocytes only N-acetylneuraminic acid has been demonstrated to occur. The applied methods include quantitative colorimetry, thin-layer chromatography and combined gas-liquid chromatography-mass spectrometry.

Identification of 9-O-acetyl-N-acetylneuraminic acid on the surface of balb/c mouse erythrocytes

Abstract For the first time 9-O-acetyl-N-acetylneuraminic acid has been unequivocally identified as the almost exclusive sialic acid of BALB/c mouse erythrocytes by gas-liquid chromatography/mass spectrometry. In human erythrocytes which were processed simultaneously N-acetylneuraminic acid could be identified as the only sialic acid. In 1010 human erythrocytes 350 nmoles of sialic acid were found and in the same number of mouse erythrocytes 440 nmoles.

The interaction ofClostridium perfringens sialidase with immobilized sialic acids and sialyl-glycoconjugates

Clostridium perfringens sialidase is adsorbed by sialic acid immobilized on adipic acid dihydrazido-Sepharose 4B and/or polymethylacrylic hydrazido-Sepharose 4B, through its carboxyl group, C-7 to C-9 side chain, or its amino function asd-neuraminic acid-β-methyl glycoside or 2-deoxy-2,3-didehydroneuraminic acid. Sialidase binding was strongest to the amino-linked adsorbents, but purification was low and the enzyme could not be eluted with substrate or free sialic acid. Low binding of the sialidase to the non-substituted, blocked supports suggested that hydrophobic interactions were involved, and this was confirmed by adsorption of the enzyme on alkyl agaroses with approximately 80% of total sialidase adsorbed on decyl-agarose. Genuine affinity chromatography of sialidases is possible on immobilized sialyl-glycoconjugates, andC. perfringens sialidase could be purified to the same specific activity as the electrophoretically homogeneous enzyme using submandibular gland mucus glycoprotein adsorbents. Sialidases fromVibrio cholerae, Arthrobacter ureafaciens, Newcastle disease virus, Fowl plague virus and Influenza A2 virus also bound to immobilized sialic acids and sialyl-glycocojugates.

Isolation and Properties of Acylneuraminate Cytidylyltransferase from Frog Liver

Publisher Summary Frog liver is a rich source for acylneuraminate cytidylyltransferase. This chapter discusses an experiment to study the isolation and properties of enzyme acylneuraminate cytidylyltransferase from frog liver and to assess its value for a ready synthesis of the CMP-glycoside of N-acetylneuraminic acid. It also describes the results from the individual purification of enzyme. The high-molecular weight of the cytidylyltransferase is remarkable. The enzyme undergoes the process of electrophoresis. The inhibition of the enzyme by heavy metal ions and iodoacetamide points to the possible involvement of SH groups in the enzyme reaction. The enzyme is stable in the frozen state, each cycle of freezing and thawing leading to an activity decrease of 15%. It is concluded through experiment that CMP-W-acetylneuraminic acid can easily be synthesized in quantitative yield with the aid of frog liver cytidylyltransferase enriched by chromatography on DEAE-cellulose.