Preparation of some new neoglycoproteins by amidination of bovine serum albumin using 2-imino-2-methoxyethyl 1-thioglycosides.

The cyanomethyl 1-thioglycosides of beta-D-galactose, 6-O-methyl-beta-D-galactose, alpha-L-arabinose, beta-D-fucose, beta-L-fucose, beta-D-glucose, beta-D-xylose, beta-D-allose, alpha-D-mannose, 2-acetamido-2-deoxy-beta-D-glucose, 2-acetamido-2-deoxy-beta-D-galactose, 2-deoxy-beta-D-glucose, and 3-O-methyl-beta-D-glucose were prepared from the respective pseudothiourea derivatives and chloroacetonitrile. The nitrile function in the aglycon of the cyanomethyl 1-thioglycosides was converted to a methyl imido ester by treatment with sodium methoxide in methanolic solutions, thereby affording the 2-imino-2-methoxyethyl 1-thioglycosides [Lee, Y.C., Stowell, C.P., & Krantz, M.J. (1976) Biochemistry 15, 3956-3963]. The stability of these reagents was investigated. The 2-imino-2-methoxyethyl 1-thioglycosides were then used to attach carbohydrates to bovine serum albumin. Amidination could be accomplished within a few hours in a pH range of 7-10. The extent of amidination could be controlled by varying the ratio of imido ester to protein amino group. These new neoglycoproteins were used to determine stereospecificity of the rabbit hepatic carbohydrate-binding system [Stowell, C.P., Lee, R.T., & Lee, Y.C. (1980) Biochemistry (following paper in this issue)].