New Set of Orthogonal Protecting Groups for the Modular Synthesis of Heparan Sulfate Fragments

2003 ◽  
Vol 5 (26) ◽  
pp. 4975-4978 ◽  
Author(s):  
Arati Prabhu ◽  
Andre Venot ◽  
Geert-Jan Boons
2005 ◽  
Vol 3 (4) ◽  
pp. 803-829 ◽  
Author(s):  
Hammed Hassan

AbstractA concise method for a stereocontrolled synthesis of a set of selectively protected disaccharides is reported. Coupling of the donor 11 onto acceptors 23 and 24, promoted by trimethylsilyl triflate-N-iodosuccinimide (TMSOTf-NIS), generated the disaccharides 25 and 26. Under typical conditions, condensation of the fully protected donor 12 onto acceptors 23 and 24 produced the disaccharides 27 and 28. The building blocks 25–28 were prepared in moderate yields having exclusive β-stereoselectivity. A unique pattern of protecting groups distinguished clearly between positions to be sulfated and functional groups remaining as free hydroxyl groups. Acetyl and/or levulinoyl esters temporarily protected the positions to be sulfated, while benzyl ethers were used for permanent protection. The anomeric positions were protected as allyl ethers, whereas the 4′-positions were masked as p-methoxybenzyl (PMB) ethers. The orthogonality of the PMB and allyl groups can then be used for further elongation of the chain by recurrent deprotection and activation steps. The hydroxyl group, OH-6, of glucosamine moieties was protected as a TBDPS ether to avoid oxidation. A five-step deprotection/sulfonation sequence was applied to the disaccharide 27 to generate the corresponding sulfated [β-D-GlcUA-2-OSO3Na-(1→4)-β-D-Glc pNAc]-(1→O-Pro) 34.


2013 ◽  
Vol 15 (2) ◽  
pp. 342-345 ◽  
Author(s):  
Chengli Zong ◽  
Andre Venot ◽  
Omkar Dhamale ◽  
Geert-Jan Boons

2009 ◽  
Vol 131 (47) ◽  
pp. 17394-17405 ◽  
Author(s):  
Sailaja Arungundram ◽  
Kanar Al-Mafraji ◽  
Jinkeng Asong ◽  
Franklin E. Leach ◽  
I. Jonathan Amster ◽  
...  

2014 ◽  
Vol 12 (13) ◽  
pp. 2087-2098 ◽  
Author(s):  
Omkar P. Dhamale ◽  
Chengli Zong ◽  
Kanar Al-Mafraji ◽  
Geert-Jan Boons

A streamlined approach has been developed for the preparation of modular disaccharide building blocks for the assembly of libraries of HS oligosaccharides that avoids postglycosylation oxidation.


Author(s):  
U. Frevert ◽  
S. Sinnis ◽  
C. Cerami ◽  
V. Nussenzweig

Malaria sporozoites, which invade hepatocytes within minutes after transmission by an infected mosquito, are covered with the circumsporozoite (CS) protein, which in all Plasmodium species contains the conserved region II-plus. This region is also found as a cell-adhesive motif in a variety of host proteins like thrombospondin, properdin and the terminal complement components.The CS protein with its region II-plus specifically binds to heparan sulfate proteoglycans (HSPG) on the basolateral surface of hepatocytes in the space of Disse (FIG. 1), to certain basolateral cell membranes and basement membranes of the kidney (FIG. 2) as well as to heparin in the granules of connective tissue mast cells. The distribution of the HSPG receptors for the CS protein was examined by incubation of Lowicryl K4M or LR White sections of liver and kidney tissue with the recombinant CS ligand, whose binding sites were detected with a monoclonal anti-CS antibody and protein A gold.


1996 ◽  
Vol 75 (01) ◽  
pp. 168-174 ◽  
Author(s):  
Shigeru Tokita ◽  
Morio Arai ◽  
Naomasa Yamamoto ◽  
Yasuhiro Katagiri ◽  
Kenjiro Tanoue ◽  
...  

SummaryTo study the pathological functions of anti-phospholipid (anti-PL) antibodies, we have analyzed their effect on platelet function. We identified an IgG anti-PL mAb, designated PSG3, which cross-reacted specifically with glycoprotein (GP) IIIa in human platelets and inhibited platelet aggregation. PSG3 bound also to certain polyanionic substances, such as double-stranded DNA, heparan sulfate, dextran sulfate and acetylated-LDL, but not to other polyanionic substances. The binding of PSG3 to GPIIIa was completely inhibited by heparan sulfate and dextran sulfate, indicating that PSG3 recognizes a particular array of negative charges expressed on both GPIIIa and the specified polyanionic substances. Since neither neuraminidase- nor endoglycopeptidase F-treatment of GPIIIa had any significant effect on the binding of PSG3, this array must be located within the amino acid sequence of GPIIIa but not in the carbohydrate moiety. Reduction of the disulfide bonds in GPIIIa greatly reduced its reactivity, suggesting that the negative charges in the epitope are arranged in a particular conformation. PSG3 inhibited platelet aggregation induced by either ADP or collagen, it also inhibited fibrinogen binding to activated platelets in a dose-dependent fashion. PSG3, however, did not inhibit the binding of GRGDSP peptide to activated platelets. These results suggest that the PSG3 epitope on GPIIIa contains a particular array of negative charges, and possibly affects the fibrinogen binding to GPIIb/IIIa complex necessary for platelet aggregation.


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