Metabolism of 4‐O‐Methyl‐N‐acetylneuraminic Acid a Synthetic Sialic Acid

Abstract

1. 4-0-Methyl-N-acetylneuraminic acid shows a strong positive periodate-thiobarbiturate reaction. The mechanism of dye formation in this test for sialic acids is discussed in view of the studies already published.2. An efficient preparation of a tritium-labelled 4-0-methyl-N-acetylneuraminic acid, with high specific radioactivity, by an oxymercuration-demercuration procedure is presented.3. Sialyltransferase activities in microsomal fractions of equine liver using desialylated fetuin are studied. The enzyme activity, assayed in a radioactive procedure, shows an apparent K , value for CMP-N-acetylneuraminic acid of 0.7 mM, whereas this value is 3.4 mM for CMP-4-0-methyl-N-acetylneuraminic acid. Differences are also observed in the maximal velocity for the two substrates.4. The equine liver system can be used to prepare substantial amounts of fetuin containing radioactive N-acetylneuraminic acid or 4-0-methyl-N-acetylneuraminic acid. The isolated reaction products show similar sialic acid release by treatments with acid or fowl-plague virus neuraminidase. In contrast, 4-0-methyl-N-acetylneuraminic acid-fetuin displays a marked resistance to desialylation by Vibrio cholerae neuraminidase.5. Free 4-0-methyl-N-acetylneuraminic acid is completely resistant to the action of acylneuraminate pyruvate-lyase. It does not inhibit the enzymic cleavage reaction of N-acetylneuraminic acid.6. The influence of a substitution at C-4 of neuraminic acid on the enzymatic reaction mechanisms is discussed.The acylneuraminic acids (sialic acids), widely distributed in animal tissues, are important components of oligosaccharides, glycolipids and glycoproteins. The occurrence and nature of various Nacylated and O-acylated neuraminic acids is now well documented [l -31, and the pattern distribution is characteristic for the animal species. Sialic acids are implicated in many cellular processes [4], and the high number of the 0-acylated derivatives points to the importance of understanding the biological role of these substances. In a preliminary approach, a precise evaluation of the behaviour of the main enzymes involved in the metabolism of sialic acids is

Neuraminidase Activity as a Potential Enzymatic Marker for Rapid Detection of Airborne Viruses

“…We confirmed that a substrate specific to viral neuraminidases can discriminate between viral and bacterial neuraminidase activities as previously described in the literature (Beau and Schauer 1980;Liav 1995;Liav et al 1999;Shimasaki et al 2001). We demonstrated that this substrate could be used to detect viral neuraminidase from air samples without interference from high bacterial load.…”

“…The 4-methoxy-Neu5Ac specificity to detect viral neuraminidase was already challenged in the literature with several viral strains, oral streptococci and Vibrio cholerae bacterial strains as well as mammalian cells (Beau and Schauer 1980;Shimasaki et al 2001). In this study we tested the specificity of this substrate against other bacterial strains in order to justify the use of this substrate to detect viral neuraminidase from swine barn air samples contaminated with high bacterial loads.…”

“…However, it is known in Taylor (1996) 2 Taylor (1996) 3 Bowden et al (2001) 4 Seth and Shaila (2001) 5 Nishikawa et al (1977) 6 Bardeletti et al (1975) the literature that modifications in positions 4, 7, 8, and 9 of the Neu5Ac group change the specificity of the substrate toward different neuraminidase sources (Beau and Schauer 1980;Corfield et al 1986;Liav et al 1999;Shimasaki et al 2001;Varki and Diaz 1983). The 4-methoxy-Neu5Ac was demonstrated to be specific toward all viral neuraminidases tested and unrecognized by mammalian and bacterial neuraminidases (Beau and Schauer 1980;Liav et al 1999;Shimasaki et al 2001). The 4,7-dimethoxy-Neu5Ac substrate was found to be specific to influenza virus neuraminidase only (Liav et al 1999;Shimasaki et al 2001).…”

4‐Methylumbelliferyl 5‐Acetamido‐3,4,5‐trideoxy‐α‐D‐manno‐2‐nonulopyranosidonic Acid: Synthesis and Resistance to Bacterial Sialidases

“…Substitution of the OH group at C(4) by an AcO group [2] [2S] prevents hydrolysis of the glycosidic groups of sialic acids by bacterial sialidases, too. In addition, methylation of the OH group at C(4) [26] strongly reduces the hydrolysis rate of this sialic acid by V. cholerae sialidase. These residues also seem to prevent or hinder binding of sialic acid to the active center of sialidase, as 4-0,N-diacetylneuraminic acid does not competitively inhibit sialidase action, similar to the 4-deoxy-NeuSAc 1 tested here.…”

N ‐Acetylneuraminic Acid Derivatives and Mimetics as Anti‐Influenza Agents

“…In particular, bacterial sialidases often exhibit reduced ability to hydrolyze sialosides with alterations at C-4 [94][95][96]. In particular, bacterial sialidases often exhibit reduced ability to hydrolyze sialosides with alterations at C-4 [94][95][96].…”