Development of specific inhibitors for heparin-binding proteins based on the cobra cardiotoxin structure: an effective synthetic strategy for rationally modified heparin-like disaccharides and a trisaccharide.
Recently, a new heparin disaccharide-binding site on the convex side of cobra cardiotoxin (CTX) was identified by NMR spectroscopy and molecular modeling. To further characterize this site two heparin-like disaccharides were synthesized for binding studies with CTX, and a trisaccharide was synthesized for testing the sequence of the disaccharide binding to CTX. Thus six differentially protected monosaccharide building blocks (three l-iduronic acids and three d-glucosamines) were prepared. These include a l-iduronic acid elongation building block namely methyl 2-O-acetyl-4-O-levulinoyl-3-O-pivaloyl-alpha-l-idopyranosyluronate trichloroacetimidate for which a single-crystal X-ray structure was determined to have M(r)=576.79, a=9.3098(11)A alpha=90 degrees , b=10.3967(12)A beta=90 degrees , c=28.026(3)A gamma=90 degrees , V=2712.7(6)A(3), P2(1)2(1)2(1), Z=4, mu=0.71073A, and R=0.0378 for 7586 observed reflections. It shows that the molecular structure of the donor is in the (1)C(4) conformation with significant 1,3-diaxial interactions between O-1 and O-3 as well as O-2 and O-4. The disaccharides and trisaccharide vary in the degree and position of O- and N-sulfation. The pivaloyl group was used as permanent protecting group of hydroxyl. The levulinoyl group was used as the temporary protecting group to protect the hydroxyl for elongation.
Ke
Weijun
W
Institute for Biological Sciences, National Research Council, Ottawa, ON, Canada K1A 0R6.
Whitfield
Dennis M
DM
Brisson
Jean-Robert
JR
Enright
Gary
G
Jarrell
Harold C
HC
Wu
Wen-guey
WG
D000818:Animals; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002352:Carrier Proteins / Q000037:antagonists & inhibitors; D004179:Cobra Cardiotoxin Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D004187:Disaccharides / Q000138:chemical synthesis* / Q000494:pharmacology; D006493:Heparin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D007067:Iduronic Acid / Q000737:chemistry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000494:pharmacology
D002352:Carrier Proteins; D004179:Cobra Cardiotoxin Proteins; D004187:Disaccharides; D014312:Trisaccharides; C464536:heparin disaccharide; D007067:Iduronic Acid; D006493:Heparin