Thin-layer chromatography and polyacrylamide gel electrophoresis-based assays for sialyltransferases using tetramethylrhodamine-labeled acceptors.
Two novel assay systems for the determination of sialyltransferase activity using a tetramethylrhodamine-labeled disaccharide Galbeta1-4GlcNAc (2) as the acceptor are described. The TMR-labeled disaccharide 2 was synthesized by directly coupling Galbeta1-4GlcNAc-O-(CH(2))(6)NH(2) (1) with 5-tetramethylrhodamine N-hydroxysuccinimide ester. The K(m) value for compound 2 obtained with alpha-2,6-sialyltransferase from rat liver (EC 2.4.99.1) was 160 +/- 20 microM. After incubation of compound 2 with sialyltransferase the product and the unreacted acceptor substrate were separated either by thin-layer chromatography (TLC) on C-18 silica gel plates or by polyacrylamide gel electrophoresis (PAGE). The density of the spots on the TLC plates and the fluorescence of the bands on the gel were quantified. The assay conditions were optimized using crude bovine colostrum extract and also alpha-2, 6-sialyltransferase from rat liver. The detection limits for the TLC and PAGE assays were 1 and 0.4 microU of the rat liver enzyme, respectively. Either assay allows the parallel investigation of several samples at a time and is useful for the testing of fractions during enzyme purification.
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Industrial Research Ltd., Gracefield Research Centre, Lower Hutt, New Zealand. u.hubl@irl.cri.nz
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D000818:Animals; D002240:Carbohydrate Sequence; D002417:Cattle; D002855:Chromatography, Thin Layer / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D051381:Rats; D012235:Rhodamines / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012799:Sialyltransferases / Q000032:analysis*
D012235:Rhodamines; C005358:tetramethylrhodamine; D012799:Sialyltransferases