Method for synthesis of sialylated products using reversible sialylation

1. A method for sialylating an acceptor glycoconjugate comprising the steps of admixing in a vessel the following components to form a reaction mixture:

a) a sialic acid donor other than a sialic acid-5′-nucleotide monophosphate (NMP);

b) an acceptor glycoconjugate; and

c) catalytic amount of exogenous mammalian ST3Gal-II sialyltransferase, under conditions such that a sialylated acceptor glycoconjugate is formed in the reaction mixture.

2. The method of claim 1 , wherein the sialic acid donor is selected from the group consisting of glycoprotein and glycolipid.

3. The method of claim 2 , wherein the glycoprotein is selected from the group consisting of mucin core-2 glycoprotein, mucin core-1 glycoprotein, fetuin, and Cowper's gland mucin (CGM).

4. The method of claim 2 , wherein the glycolipid is a ganglioside.

5. The method of claim 1 , wherein the acceptor glycoconjugate is selected from the group consisting of glycoprotein and glycolipid.

6. The method of claim 1 , wherein the mammalian ST3Gal-II sialyltransferase is selected from the group consisting of recombinant rat ST3Gal-II and human ST3Gal-II.

7. The method of claim 1 , wherein the conditions comprise a pH from 5.0 to 6.0.

8. The method of claim 1 , wherein the conditions comprise a pH of 5.6.

9. The method of claim 1 , wherein the sialic acid donor has a detectable label incorporated into the sialic acid moiety that is transferred to the acceptor glycoprotein.

10. The method of claim 9 , wherein the detectable label is a radioactive isotope.

11. The method of claim 10 , wherein the radioactive isotope is selected from the group consisting of tritium ( 3 H) and 14 C.

12. The method of claim 1 , wherein the reaction mixture further comprises 5′-cytidine monophosphate.