Sialic acid is a monosaccharide found at the non-reducing termini of glycoproteins and glycolipids. Cell surface sialylation is dynamically regulated by sialidases, enzymes that hydrolytically cleave sialic acid from glycoproteins and glycolipids.  Sialidases are implicated in numerous physiological and pathological processes, yet the mechanisms by which they exert their effects remain unclear.  Detailed knowledge of sialidases' substrate specificity could provide insight into their mechanism of action.  Accordingly, we developed methods to determine both the glycan and aglycone specificity of sialidases.  First, we report an assay to identify structural elements within oligosaccharides that contribute to substrate specificity.  We demonstrate application of this assay to both human and bacterial sialidases.  Second, we describe a method to covalently capture sialidase-substrate interactions in a cellular context.  This approach can be combined with mass spectrometry to identify the aglycone component of sialidase substrates. These tools offer an initial step toward defining biological mechanisms for sialidases.

New tools to discover sialidase substrates

245th National Meeting (2013)

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