The susceptibility of various acylneuraminates to yV-acetylneuraminate pyruvatelyase (EC 4. l .3.3) from Clostridium perfringens was studied. Different substituents of the amino group of neuraminic acid (7V-glycoloyl, JV-monochloroacetyl, W-formyl and yV-succinyl groups) are of little influence on the enzyme activity when compared with W-acetylneuraminate (/f m =1.85x 10~3M). In contrast, W-monofiuoroacetylneuraminate is cleaved at a considerably lower rate (K m = lxJO" 2 M). 0-acetylation in position 4 of the Cg-chain of 7V-acetylneuraminate reduces the cleavage rate by about 80% (K m = 1.25xIO-2 M),

GC-MS has been applied to the characterization of mixtures of polyunsaturated fatty acids by way of their isopropylidene, alkylboronate, methyl ether, and trimethylsilyl ether derivatives. In our studies we found a convenient and efficient method for the oxidation of mixtures of polyunsaturated fatty acid methyl esters by osmium tetroxide. The resulting polyhdroxy compounds are easily converted into apolar derivatives for gas chromatographic separation. The mass spectra of these individual compounds were recorded as to their usefulness for complete structure elucidation. Only the trimethylsilyl ethers proved to yield all information necessary for determination of chain length as well as numbers and positions of double bonds of polyunsaturated fatty acids.

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Zusammenfassung: Aus Rindersubmaxillarismucin wird Neuraminsäure-ß-methylglykosid gewonnen. Dieses wird mit Essigsäureanhydrid zu N-Acetylneuraminsäure-methylglykosid, mit [l-14 C]Essigsäureanhydrid zu A r -[l-14 C]Acetyl-neuraminsäuremethylglykosid und mit 1.3-Dioxolandion-(2.4) zu 7V-Glykolyl -neuraminsäure -methyIglykosid quantitativ umgesetzt. Aus den acylierten Methyl-Summary : Synthesis ofN-acetylneuraminic acid from neuraminic acid ^-methylglycoside^ L Neuraminic acid ß-methy}glyco$ide was isolated from bovine submaxillary mucin. This was converted quantitatively into 7V-acetylneuraminic acid methylglycoside with acetic anhydride, into 7V-[1-14 C]acetylneuraminic acid methyIglycoside with [1-14 C]acetic anhydride, and into 7V-glycolylneuraminic acid methylglycoside with l,3-dioxolan-2,4-dione.

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