Properties and partial purification of sialate-O-acetyltransferase from bovine submandibular glands.
The O-acetylation of sialic acids in various positions is a frequent modification of these residues in glycoproteins and glycolipids of higher animals and some bacteria. Sialic acid O-acetylation is involved in the regulation of many cell biological and pathophysiological events. Since the properties and the structural and molecular genetic aspects of the eukaryotic sialate O-acetyltransferases are not yet known, we attempted to isolate the enzyme from bovine submandibular glands. O-Acetyltransferase was solubilised from its microsomal location with a zwitterionic detergent and enriched by approximately 50-fold in three steps, including affinity chromatography on coenzyme A. It exhibits a molecular mass of 150-160 kDa. Evidence was obtained for the putative existence of a low-molecular-mass, dialysable enzyme activator. The enzyme showed best activity with CMP-N-acetylneuraminic acid (CMP-Neu5Ac), followed by N-acetylneuraminic acid (Neu5Ac). These compounds, as well as AcCoA, have high affinity for both the microsome-bound and the partially purified O-acetyltransferase. CoA is a strong inhibitor. N-Acetyl-9-O-acetylneuraminic acid was found to be the main reaction product. No evidence was obtained for the involvement of an isomerase that might be responsible for the migration of O-acetyl groups within the sialic acid side chain.
Lrhorfi
L Aicha
LA
Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstr. 40, D-24098 Kiel, Germany.
Srinivasan
G Vinayaga
GV
Schauer
Roland
R
D000123:Acetyltransferases / Q000302:isolation & purification / Q000378:metabolism; D000217:Acyltransferases / Q000302:isolation & purification* / Q000378:metabolism; D000818:Animals; D002417:Cattle; D008861:Microsomes / Q000201:enzymology*; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D012995:Solubility; D013363:Submandibular Gland / Q000201:enzymology*
D000217:Acyltransferases; D000123:Acetyltransferases; C082760:sialate 9-O-lactoyltransferase; D019158:N-Acetylneuraminic Acid