β-elimination and reduction reactions and some applications of dimethylsulfoxide on submaxillary glycoproteins

Abstract

It has been shown that dimethylsulfoxide is useful in separating protein contaminants and minor mucins from the submaxillary glycoproteins prepared by the method of Tettamanti, G. and Pigman, W. (1968) Arch. Biochem. Biophys., 124, 41–50. In addition, alkaline dimethylsulfoxide was found to greatly accelerate the β-elimination reaction of glycoproteins. As this procedure does not produce diffusible protein fragments, it should be of value in studies of the protein core and for the investigation of those protein-carbohydrate linkages that are resistant to treatment by alkali. Optimal conditions for carrying out the β-elimination and reduction reactions of bovine submaxillary glycoprotein in aqueous alkaline NaBH 4 systems have been described. Under such conditions, the conversion of 2-aminopropenoic and 2-amino-2-butenoic acid residues into alanine and α-aminobutyric acid, respectively, is complete. This reduction procedure is of a broad application and can be used for the reduction of the phenylhydrazone derivatives of α-keto acids to the corresponding amino acids. A comparison of our procedure with that described by Simpson, L. D., Hranisavljevic, J. and Davidson, E. A. (1972) Biochemistry, 11, 1849–1856, shows that the method outlined here is superior both in efficiency and for quantitative recovery of unsaturated hydroxyamino acids.