Protease and binding polypeptide for O-glycoproteins

A method of binding to an O-glycan, O-glycopeptide and/or O-glycoprotein, wherein the method comprises:

• contacting a sample comprising the O-glycan, O-glycopeptide and/or O-glycoprotein with a polypeptide which is capable of binding to an O-glycan or O-glycoprotein and which lacks or has reduced endoprotease activity specific for O-glycosylated proteins, wherein the polypeptide comprises:
• (a) the amino acid sequence of SEQ ID NO:
• 5 or SEQ ID NO:
• 20;
• (b) an amino acid sequence which is at least 95% identical to the amino acid sequence of SEQ ID NO:
• 5 or SEQ ID NO:
• 20;
• or
• (c) an amino acid sequence which is a fragment of the sequence of SEQ ID NO:
• 5 or SEQ ID NO:
• 20 or a fragment of an amino acid which is at least 95% identical to the amino acid sequence of SEQ ID NO:
• 5 or SEQ ID NO:
• 20;
• and
• determining whether or not an O-glycan, O-glycopeptide and/or O-glycoprotein has been bound and/or separating the O-glycan and any linked glycoprotein, the O-glycopeptide or O-glycoprotein from the resulting mixture,
• wherein the method is for the purpose of isolating an O-glycan or linked glycoprotein, O-glycopeptide or O-glycoprotein from the sample.