- Chemical synthesis of 4-azido-β-galactosamine derivatives for inhibitors of N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase
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Chondroitin sulfate E (CS-E) plays a crucial role in diverse processes ranging from viral infection to neuroregeneration. Its regiospecific sulfation pattern, generated by N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST), is the main structural determinant of its biological activity. Inhibitors of GalNAc4S-6ST can serve as powerful tools for understanding physiological functions of CS-E and its potential therapeutic leads for human diseases. A family of new 4-acylamino-β-GalNAc derivatives and 4-azido-β-GalNAc derivatives were synthesized for their potential application as inhibitors of GalNAc4S-6ST. The target compounds were evaluated for their inhibitory activities against GalNAc4S-6ST. The results revealed that 4-pivaloylamino- and 4-azido-β-GalNAc derivatives displayed evident activities against GalNAc4S-6ST with IC50 value ranging from 0.800 to 0.828?mM. They showed higher activities than benzyl D-GalNAc4S that was used as control.
- Hor, Seanghai,Kodama, Takumi,Sugiura, Nobuo,Kondou, Hikaru,Yanagida, Mio,Yanagisawa, Keiya,Shibasawa, Aoki,Tsuzuki, Bunta,Fukatsu, Naoto,Nagao, Kazuya,Yamana, Kenji,Hidari, Kazuya I. P. J.,Watanabe, Hideto,Habuchi, Osami,Nakano, Hirofumi
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p. 477 - 491
(2018/09/20)
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- Chondroitin-4-O-sulfatase from Bacteroides thetaiotaomicron: Exploration of the substrate specificity
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Bacterial sulfatases can be good tools to increase the molecular diversity of glycosaminoglycan synthetic fragments. A chondroitin 4-O-sulfatase from the human commensal bacterium Bacteroides thetaiotaomicron has recently been identified and expressed. In order to use this enzyme for synthetic purposes, the minimal structure required for its activity has been determined. For that, four 4-O-sulfated monosaccharides and one 4-O-sulfated disaccharide have been synthesized and used as substrates with the sulfatase. The minimum structure was shown to be a disaccharide but in contrast to the natural substrate, which must have a 4,5-insaturation, the enzyme accepts as substrate, a disaccharide with a saturated glucuronic acid at the non-reducing end and even a glucopyranosyl moiety without the carboxylic acid functionality.
- Malleron, Annie,Benjdia, Alhosna,Berteau, Olivier,Le Narvor, Christine
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- Elucidation of the mechanism of polysaccharide cleavage by chondroitin AC lyase from Flavobacterium heparinum
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Chondroitin AC lyase from Flavobacterium heparinum degrades chondroitin sulfate glycosaminoglycans via an elimination mechanism resulting in disaccharides or oligosaccharides with Δ4,5-unsaturated uronic acid residues at their nonreducing end. Mechanistic details concerning the ordering of the bond-breaking and -forming steps of this enzymatic reaction are nonexistent, mainly due to the inhomogeneous nature of the polymeric substrates. The creation of a new class of synthetic substrates for this enzyme has allowed the measurement of defined and reproducible kcat and Km values and has expanded the range of mechanistic studies that can be performed. The primary deuterium kinetic isotope effect upon kcat/Km for the abstraction of the proton α to the carboxylic acid was measured to be 1.67 ± 0.07, showing that deprotonation occurs in a rate-limiting step. Using substrates with leaving groups of differing reactivity, a flat linear free energy relationship was produced, indicating that the C4-O4 bond is not broken in a rate-determining step. Taken together, these results strongly suggest a stepwise mechanism. Consistent with this was the measurement of a secondary deuterium kinetic isotope effect upon kcat/Km of 1.01 ± 0.03 on a 4-{2H}-substrate, indicating that no sp2 character is developed at C4 during the rate-limiting step, thereby ruling out a concerted syn-elimination.
- Rye, Carl S.,Withers, Stephen G.
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p. 9756 - 9767
(2007/10/03)
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- Synthesis of O-(2-O-sulfo-α-L-idopyranosyluronic acid)-(1 → 3)-2- acetamido-2-deoxy-4-O-sulfo-D-galactopyranose trisodium salt, a disaccharide fragment of dermatan sulfate
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Benzyl 2-acetamido-2-deoxy-α, and β-D-glucopyranoside were converted in high yield into the corresponding D-galacto analogues through a three- step procedure. These later were transformed in a straightforward manner into benzyl 2-acetamido-4-O-acetyl-6-O-benzyl-2-deoxy-α, and β-D- galactopyranoside, respectively, which served as acceptors in glycosylation reactions with variously activated derivatives of methyl 2-O-benzoyl-3,O- benzyl-4-O-chloro-acetyl-L-idopyranuronate. Condensation of the chloride derivative promoted by silver triflate led unexpectedly to the formation of the β-linked disaccharide, whereas the trichloroacetimidoyl derivative afforded the expected α-linked disaccharide in 63% yield. O- Dechloroacetylation of this later, followed by 4-methoxybenzylation at O-4 of the uronic acid moiety, saponification of the esters, O-sulfonation of the free hydroxyls, and catalytic hydrogenation provided the title disaccharide in high yield, as its sodium salt.
- Rochepeau-Jobron, Laurence,Jacquinet, Jean-Claude
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p. 181 - 191
(2007/10/03)
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