Chondroitin polymerase and DNA encoding the same

1. An isolated protein that comprises SEQ ID NO: 2, a fragment of SEQ ID NO: 2, or an amino acid sequence identical to SEQ ID NO: 2 except that it has 1 to 30 of its amino acid residue(s) deleted, or substituted, or 1 to 30 amino acid residues inserted within the sequence of SEQ ID NO: 2;

wherein said isolated protein has chondroitin polymerase activity; and

wherein said isolated protein is not membrane-bound.

2. The isolated protein of claim 1 that consists of SEQ ID NO: 2.

3. The isolated protein of claim 1 that consists of a fragment of SEQ ID NO: 2 that has chondroitin polymerase activity.

4. The isolated protein of claim 1 that comprises a sequence identical to SEQ ID NO: 2 except that it has 1 to 30 of its amino acid residue(s) deleted, substituted, or 1 to 30 amino acid residues inserted within the sequence of SEQ ID NO: 2, wherein said isolated protein has chondroitin polymerase activity.

5. The isolated protein of claim 1 that has been expressed by a host cell other than E. coli.

6. The isolated protein of claim 1 , which has been isolated from a host cell that is a plant cell, yeast cell, insect cell or mammalian cell.

7. The isolated protein of claim 1 , which has been isolated from a host cell that is Bacillus subtilis .

8. The isolated protein of claim 1 that has been partially purified from other culture medium components or from other components of a cellular extract.

9. The isolated protein of claim 1 that has been fully purified from other culture medium components or from other components of a cellular extract.

10. The isolated protein of claim 1 that is soluble.

11. The isolated protein of claim 1 , wherein said chondroitin polymerase activity:

transfers GLcUA and GalNAc alternately to a non-reduced terminal of a sugar chain from a GlcUA donor and a GalNAc donor, respectively;

transfers GlcUA to an oligosaceharide having GalNAc on its non-reduced terminal and a chondroitin backbone from a GlcUA donor, but does not substantially transfer GalNAc to the oligosaccharide from a GalNAc donor;

transfers GalNAc to an oligosaceharide having GlcUA on its non-reduced terminal and a chondroitin backbone from a GalNAc donor, but does not substantially transfer GlcUA to the oligosaccharide from a GlcUA donor; and

acts in the presence of Mn 2+ ion but does not substantially act in the presence of Ca 2+ ion, Cu 2+ ion or ethylenediaminetetraacetic acid;

wherein GlcUA represents D-glucuronic acid; and GalNAc represents N-acetyl-D-galactosamine.

12. The isolated protein of claim 1 in frozen or freeze-dried form.

13. A composition comprising the isolated protein of claim 1 and a pharmaceutically acceptable carrier or a carrier acceptable in a reagent.

14. A culture medium comprising the isolated protein of claim 1 in soluble, secreted form.

15. The isolated protein of claim 1 that has been immobilized on a carrier.

16. An isolated protein that comprises SEQ ID NO: 2, a fragment of SEQ ID NO: 2, or an amino acid sequence identical to SEQ ID NO: 2 except that it has 1 to 30 of its amino acid residue(s) deleted, or substituted, or 1 to 30 amino acid residues inserted within the sequence of SEQ ID NO: 2;

wherein said isolated protein has chondroitin polymerase activity; and

wherein said isolated protein is not membrane-bound and is soluble in a culture medium.