Detection of Polysialosyl-Containing Glycoproteins in Brain Using Prokaryotic-Derived Probes

Several laboratories have described a class of high molecular weight surface sialoglycoproteins that function in neural cell adhesion and brain development. This chapter discusses the probes that recognize or synthesize polysialic acid containing α-2,8-ketosidic linkages. These probes have been used in combination with structural studies to prove the presence of polysialosyl carbohydrate units in membranes of embryonic chick and rat brains; to quantitate the amount of [¹⁴C]NeuNAc incorporated specifically into α-2,8-1inked polysialosyl units in neural cell adhesion molecule (N-CAM) by a CMP-NeuNAc:poly- α-2,8-sialosyl sialy ferase; and to show that the polysialic acid on N-CAM has a direct effect on N-CAM mediated adhesion and that the amount of this carbohydrate is important for normal development of nerve tissue. This chapter discusses the development and use of these probes to detect polysialosyl carbohydrate units in brain and bacterial glycoconjugates. The chapter also discusses the use of the prokaryotic-derived probes to detect polysialosyl-containing glycoprotein in brain.