Abstract
Glycans of glycoproteins play many important roles, such as cell-cell interaction and cell surface recognitions. There are two ways to obtain the glycans from glycoproteins, enzymatic digestions and hydrazinolysis. We have been using an enzymatic method using glycopeptidase-A to prepare glycans from the P0 and the PASII/PMP22 glycoproteins in peripheral nerves, and determined their structures containing sulfated glucuronic acids (S-GlcA). The S-GlcA, known as HNK-1 carbohydrate epitope, is found by immunological observations in many adhesion glycoproteins in CNS and PNS, including N-CAM, MAG, L1, P0 and PMPII/PASII. and is postulated to be associated with cell adhesion, cell migration, and brain memory functions. I focused on other adhesion glycoproteins and this time preferred hydrazinolysis to prepare glycans from total brain proteins. Many types of glycans were obtained, however; glycans containing S-GlcA could not be found. A question arose whether hydrazinolysis is applicable to the glycans containing S-GlcA. The proteins, including P0 and PASII/PMP22, from PNS were subjected for the hydrazinolysis, almost all the glycans containing S-GlcA were degraded, whereas other sulfated glycans and sialylated glycans were recovered in expected amounts. It indicates that hydrazinolysis is not applicable for the glycans containing GlcA or S-GlcA. This must be one of the reasons why the structures of almost all glycans containing S-GlcA have not been reported so far, although the immunological observations tell us there are many glycoproteins containing the HNK-1 epitopes. [J Physiol Sci. 2007;57 Suppl:S142]
