Hakomori methylation

Hakomori methylation analysis, and preparation and GLC gf the PAAN derivatives (4), were used to determine the linkages. C NMR of partially hydrolysed samples confirmed the octasaccharide repeat unit, the beta linkages and the presence of the carboxylic acids. 

Hakomori methylation of polysaccharides containing uronic acid residues results in their complete esterification. The ester group in the esterified residue (A in 12) is electron-withdrawing, allowing the hydrogen attached to C5 to become sufficiently acidic that on treatment with base it is eliminated giving the 4,5-unsaturated residue (B in 12). If the uronic acid is 4-linked, the substituent at C-4 is eliminated (Lindberg et al., 1975). 

Alkylation with alkyl halides and methylsulfinyl anion in dimethyl sulfoxide (Hakomori methylation)... 

Methylation of a carbohydrate is most practically achieved by using the Hakomori procedure,9 which has largely replaced the Purdie, Haworth, and Kuhn methylation methods. 

Sakakura, C, Sweeney, E.A., Shirahama, T., Ruan, F., Solca, F., Kohno, M., Hakomori, S-1., Fischer, E.H. Igarashi, Y., 1997, Inhibition ofMAP kinase by sphingosine and its methylated derivative, N,N-dimethylsphingosine A correlation with induction of apoptosis in solid tumor cells,/nt/. 7. Oncol. 11 31-39. 

Methylation analysis was run by the method of Hakomori ( ), followed by hydrolysis with trifluoracetic acid, sodium borohydride reduction, and acetylation. 6LC was performed on a Hewlett-Packard 5970, used as an inlet for a mass spectrometer. Molecular weight was determined on a Sephacryl S-500 column (2.6 x 70 cm), using deionized water as solvent, upward flow, 2.75 ml/min, and detection by refractive index monitor. Model R-401 (Waters Associates). 

Sweeney, E.A., Sakakura, C., Shirahama, T., Masamune, A., Ohta, H., Hakomori, S-I. and Igarashi, Y., 1996, Sphingosine and its methylated derivative N,N-dimethylsphingosine (DMS) induce apoptosis in a variety of human cancer cell lines, Ini. J. Cancer 66 358-366. 

Methylatiott. Hakomori reported that glycosides of polysaccharides can bt rapidly permethylated by treatment with dimsylsodium in DMSO followed by reaction with methyl iodide ... 

Igarashi, Y., Hakomori, S., Toyokuni, T., Dean, B., Fujita, S., Sugimoto, M., Ogawa, T., el-Ghendy, K., and Racker, E., Effect of chemically well-defined sphingosine and its N-methyl derivatives on protein kinase C and src kinase activities, Biochemistry, 28 (1989) 6796-6800. 

Methylation is the most widely used method to determine the position of the glycosyl linkages.Permethylation of glycolipids can be done according to the methods of Hakomori (32) and Ciucanu and Kerek (33). The permethylated derivatives are hydrolyzed and the products converted into partially methylated alditol acetates and identified by gas chromatography-mass spectrometry ( CG-MS) (34). 

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