Nature and biosynthesis of sialic acids in the starfish Asterias rubens. Identification of sialo-oligomers and detection of S-adenosyl-L-methionine: N-acylneuraminate 8-O-methyltransferase and CMP-N-acetylneuraminate monooxygenase activities.
Mass spectrometric and NMR spectroscopic analyses of bound sialic acids from the starfish Asterias rubens revealed the presence of N-acetylneuraminic acid (4%), N-acetyl-8-O-methylneuraminic acid (12%), N-acetyl-9-O-acetyl-8-O-methylneuraminic acid (less than 1%), N-glycoloylneuraminic acid (19%), N-glycoloyl-8-O-methylneuraminic acid (47%), and N-glycoloyl-9-O-acetyl-8-O-methylneuraminic acid (18%). Analysis of sialo-oligomeric material, obtained after mild acid hydrolysis, demonstrated that N-glycoloyl-8-O-methylneuraminic acid can occur as di- and tri-oligomers, linked through the anomeric center and the N-glycoloyl moiety, Neu5Gc8Me-alpha(2----O5)-Neu5Gc8Me and Neu5Gc8Me-alpha(2----O5)-Neu5Gc8Me-alpha (2----O5)-Neu5Gc8Me. Studies on the biosynthesis of N-acyl-8-O-methylneuraminic acid in A rubens, using the tracer S-adenosyl-L-[methyl-14C]methionine, showed that N-acylneuraminate 8-O-methyltransferase activity was present predominantly in the membrane fraction. CMP-N-acetylneuraminic acid monooxygenase activity was found in the soluble protein fraction, in agreement with investigations on the corresponding vertebrate enzyme.
Bergwerff
A A
AA
Bijvoet Center, Department of Bio-Organic Chemistry, Utrecht University, The Netherlands.
Hulleman
S H
SH
Kamerling
J P
JP
Vliegenthart
J F
JF
Shaw
L
L
Reuter
G
G
Schauer
R
R
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D009682:Magnetic Resonance Spectroscopy; D008780:Methyltransferases / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000032:analysis*; D012794:Sialic Acids / Q000096:biosynthesis*; D013215:Starfish / Q000378:metabolism*
D012794:Sialic Acids; D012436:S-Adenosylmethionine; D006899:Mixed Function Oxygenases; C074383:CMPacetylneuraminate monooxygenase; D008780:Methyltransferases; C074384:N-acylneuraminate 8-0-methyltransferase