Methods for synthesis of sulfated saccharides
The present invention provides methods, processes and reaction mixtures, which produce sulfated heparosan polysaccharides. This invention also provides methods and reaction mixtures for the synthesis of N-deacetylate N-sulfate derivatives of non-sulfated N-acetyl heparosan (HS) polysaccharides.
1. A process for the synthesis of an epimerically enriched form of a sulfated heparosan polysaccharide, comprising contacting an acceptor heparosan polysaccharide with the following in a mixture:
(i) a 3′-phosphoadenosine 5′-phosphosulfate (PAPS) sulfate donor;
(ii) at least one sulfotransferase;
(iii) a p-nitrophenyl sulfate sulfate donor;
(iv) an aryl sulfatase; and
(v) an epimerase;
wherein:
(a) said at least one sulfotransferase catalyzes sulfate transfer from said PAPS sulfate donor to said acceptor heparosan polysaccharide;
(b) said PAPS, by donating said sulfate group is converted to a 3′,5′-diphosphoadenosine (PAP);
(c) said aryl sulfatase catalyzes sulfate transfer from said p-nitrophenyl sulfate sulfate donor to said PAP, thereby regenerating PAPS; and
(d) said epimerase catalyzes conversion of said acceptor heparosan polysaccharide to its epimer;
thereby synthesizing an epimerically enriched form of a sulfated heparosan polysaccharide in which the uronic acid residues are not sulfated.
2. The process of claim 1 , wherein said acceptor heparosan polysaccharide is characterized by the structure of the formula I:
wherein R is a hydrogen, hydroxy, acetyl, alkoxy carbonyl, amido, alkylamido, dialkylamido, nitro, amino, alkylamino, dialkylamino, carboxyl, thio or thioalkyl group, and n is an integer.
3. The process of claim 1 , wherein said acceptor heparosan polysaccharide is characterized by the structure of the formula II:
wherein R is a hydrogen, hydroxy, acetyl, alkoxy carbonyl, amido, alkylamido, dialkylamido, nitro, amino, alkylamino, dialkylamino, carboxyl, thio or thioalkyl group, and n is an integer.
4. The process of claim 1 , wherein said acceptor heparosan polysaccharide comprises by the structure of the formula III:
wherein R is a hydrogen, hydroxy, acetyl, alkoxy carbonyl, amido, alkylamido, dialkylamido, nitro, amino, alkylamino, dialkylamino, carboxyl, thio or thioalkyl group, and n is an integer.
5. The process of claim 1 , wherein said acceptor heparosan polysaccharide is characterized by the structure of the formula IV:
and n is an integer.
6. The process of claim 1 , wherein said epimerase is a glucuronosyl C5 epimerase.
7. The process of claim 1 , wherein said p-nitrophenyl sulfate donor is at a concentration that is at least one hundred fold in excess of the concentration of PAPS in said mixture.
8. The process of claim 1 , wherein said p-nitrophenyl sulfate donor is at a concentration that is at least five hundred fold in excess of the concentration of PAPS in said mixture.
9. The process of claim 1 , wherein said reaction mixture further comprises an endoglycosidase, which catalyzes cleavage of a glycosidic linkage in said acceptor heparosan polysaccharide or in said acceptor heparosan polysaccharide epimer.
10. The process of claim 9 , wherein said endoglycosidase catalyzes cleavage of a glycosidic linkage in said acceptor heparosan polysaccharide or in said acceptor heparosan polysaccharide epimer, prior to sulfation of said acceptor heparosan polysaccharide or said acceptor heparosan polysaccharide epimer.
11. The process of claim 9 , wherein said endoglycosidase catalyzes cleavage of a glycosidic linkage in said acceptor heparosan polysaccharide or in said acceptor heparosan polysaccharide epimer, following sulfation of said acceptor heparosan polysaccharide or said acceptor heparosan polysaccharide epimer.
12. The process of claim 9 , wherein said endoglycosidase is a heparitinase or a glycuronidase.
13. The process of claim 12 , wherein said endoglycosidase is heparitinase and wherein said heparatinase is heparatinase I, heparitinase II or heparitinase III.
14. The process of claim 12 , wherein said endoglycosidase is glycuronidase and wherein said glycuronidase is Δ 4,5 -glycuronidase.
15. The process of claim 1 , wherein said acceptor heparosan polysaccharide is at a final concentration of 0.1-100 mM in said mixture.
16. The process of claim 1 , further comprising isolating the epimerically enriched sulfated heparosan polysaccharide from the mixture.
17. The process of claim 1 , wherein said sulfotransferase is an N-deacetylase-N-sulfotransferase (NDST), heparin/heparin sulfate N-sulfotransferase; heparin sulfate 2-sulfotransferase; 6-O sulfotransferase (6-OST); 3-O sulfotransferase (3-OST); 2-O sulfotransferase; or a combination thereof.
18. The process of claim 17 , wherein said sulfotransferase is NDST and wherein said NDST is selected from the group consisting of NDST1, NDST2, NDST3 or NDST4.
19. The process of claim 17 , wherein said sulfotransferase is 3-OST and wherein said 3-OST is 3-OST1.
20. The process of claim 17 , wherein said sulfotransferase is 6-OST and wherein said 6-OST is 6-OST1, 6-OST2 or 6-OST3.
21. The process of claim 20 , wherein said 6-OST is 6-OST2 and wherein said 6-OST2 is 6-OST2a or 6-OST2b.