membranes. As structural components 
of neural cell membranes, gangliosides play important roles in cell adhesion, cell recognition signal transduction and neural development. Many O-acetylated gangliosides have been described in mammalian and nonmammalian tissues. O-acetylation of hydroxyl groups is one of the most common modifications of Rutoside site Sialic acids and exist in nature at the C-4, 7, 8 and 9 hydroxyl groups. This comparatively small change in the ganglioside structure causes major changes in their physiological properties, resistance to sialidase hydrolysis and lectin binding. When the ganglioside GD1b was O-acetylated in the outer sialic acid, it became the potent inhibitor of astroblast and astrocytoma proliferation called Neurostatin. We and others have developed several synthetic methods for the enzymatic and chemical O-acetylation of commercial gangliosides, although the yields obtained were poor and the reactions led to many similar products that were very difficult to purify. In mammals, two enzyme systems are known to be responsible for O-acetylations: AcCoA:sialate-4-O-acetyltransferase and AcCoA:sialate-7-O-acetyltransferase . Identification of the sialate-O-acetyltransferase gene has been possible in some microorganisms, but not yet in eukaryotic cells. A SOAT transferring acetyl groups exclusively to C-9 in the fluorescent ganglioside analog GD3-FCHASE was isolated and cloned from Campylobacter jejuni. Using this enzyme, we present Ganglioside O-Acetylation in Outer Sialic Acids here a new method for the specific O-acetylation of outer sialic acids in gangliosides at the C-9 hydroxyl group, permitting the large scale preparation of these modified glycosphingolipids. Materials and Methods Purification of Recombinant SOAT Escherichia coli AD202 containing the construct CJL-130 from Campylobacter jejuni ATCC 43446 in pCWori+, was grown in 2 YT medium containing 150 mg/ml ampicillin and 2 g/ liter glucose. The culture was incubated at 37uC until A600 = 0.35, induced with 1 mM isopropyl 1-thio-b-D-galactopyranoside, and incubated overnight at 20uC. The cells were resuspended in buffer A containing 20 mM Tris pH 7.5, 200 mM NaCl, 5 mM bmercaptoethanol, 1 mM EDTA and a protease inhibitor cocktail. The cells were broken using an Avestin C5 Emulsiflex cell disruptor and the extract was clarified by centrifugation at 27,0006g for 30 min. The MalE-Orf11 fusion protein was purified by affinity chromatography on amylose resin, following the manufacturer’s instructions. The clarified extract was loaded on a column containing 25 ml of amylose resin at a flow rate of 1 ml/min. The column was washed with 35 ml of buffer A and then developped with 30 ml of buffer B. The 1.5 ml fractions were analysed by SDS-PAGE on a 12% gel. The fractions containing the SOAT were pooled and dialysed o/n with a buffer containing 10 mM Hepes pH 6.5 and 20 mM NaCl. The dialysed SOAT was lyophilized in aliquots and stored at 220uC until use. SOAT activity was measured in each culture batch by measuring the production of 9-O-acetyl-GD3-FCHASE product using GD3FCHASE as acceptor. One unit of SOAT activity was defined as the amount of enzyme that produces 1 mmol of 9-O-acetylated GD3-FCHASE in 1 min. Ganglioside O-Acetylation in Outer Sialic Acids Synthesis with SOAT of O-acetylated Gangliosides Different commercially available gangliosides were O-acetylated with the help of the O-acetyltransferase isolated from C. jejuni. The enzymatic reaction was modified from