<Table> Some important methods used to study glycoproteins <Tr> <Th> Method </Th> <Th> Use </Th> </Tr> <Tr> <Td> Periodic acid - Schiff stain </Td> <Td> Detects glycoproteins as pink bands after electrophoretic separation . </Td> </Tr> <Tr> <Td> Incubation of cultured cells with glycoproteins as radioactive decay bands </Td> <Td> Leads to detection of a radioactive sugar after electrophoretic separation . </Td> </Tr> <Tr> <Td> Treatment with appropriate endo - or exoglycosidase or phospholipases </Td> <Td> Resultant shifts in electrophoretic migration help distinguish among proteins with N - glycan, O - glycan, or GPI linkages and also between high mannose and complex N - glycans . </Td> </Tr> <Tr> <Td> Agarose - lectin column chromatography, lectin affinity chromatography </Td> <Td> To purify glycoproteins or glycopeptides that bind the particular lectin used . </Td> </Tr> <Tr> <Td> Lectin affinity electrophoresis </Td> <Td> Resultant shifts in electrophoretic migration help distinguish and characterize glycoforms, i.e. variants of a glycoprotein differing in carbohydrate . </Td> </Tr> <Tr> <Td> Compositional analysis following acid hydrolysis </Td> <Td> Identifies sugars that the glycoprotein contains and their stoichiometry . </Td> </Tr> <Tr> <Td> Mass spectrometry </Td> <Td> Provides information on molecular mass, composition, sequence, and sometimes branching of a glycan chain . It can also be used for site - specific glycosylation profiling . </Td> </Tr> <Tr> <Td> NMR spectroscopy </Td> <Td> To identify specific sugars, their sequence, linkages, and the anomeric nature of glycosidic chain . </Td> </Tr> <Tr> <Td> Multi-angle light scattering </Td> <Td> In conjunction with size - exclusion chromatography, UV / Vis absorption and differential refractometry, provides information on molecular mass, protein - carbohydrate ratio, aggregation state, size, and sometimes branching of a glycan chain . In conjunction with composition - gradient analysis, analyzes self - and hetero - association to determine binding affinity and stoichiometry with proteins or carbohydrates in solution without labeling . </Td> </Tr> <Tr> <Td> Dual Polarisation Interferometry </Td> <Td> Measures the mechanisms underlying the biomolecular interactions, including reaction rates, affinities and associated conformational changes . </Td> </Tr> <Tr> <Td> Methylation (linkage) analysis </Td> <Td> To determine linkage between sugars . </Td> </Tr> <Tr> <Td> Amino acid or cDNA sequencing </Td> <Td> Determination of amino acid sequence . </Td> </Tr> </Table> <Tr> <Th> Method </Th> <Th> Use </Th> </Tr> <Tr> <Td> Periodic acid - Schiff stain </Td> <Td> Detects glycoproteins as pink bands after electrophoretic separation . </Td> </Tr> <Tr> <Td> Incubation of cultured cells with glycoproteins as radioactive decay bands </Td> <Td> Leads to detection of a radioactive sugar after electrophoretic separation . </Td> </Tr>

Glycoproteins found in the plasma membrane function in what capacity