29086-03-1Relevant academic research and scientific papers
Evaluation of analogues of GalNAc as substrates for enzymes of the Mammalian GalNAc salvage pathway
Pouilly, Sabrina,Bourgeaux, Vanessa,Piller, Friedrich,Piller, Veronique
, p. 753 - 760 (2012)
Changes in glycosylation are correlated to disease and associated with differentiation processes. Experimental tools are needed to investigate the physiological implications of these changes either by labeling of the modified glycans or by blocking their biosynthesis. N-Acetylgalactosamine (GalNAc) is a monosaccharide widely encountered in glycolipids, proteoglycans, and glycoproteins; once taken up by cells it can be converted through a salvage pathway to UDP-GalNAc, which is further used by glycosyltransferases to build glycans. In order to find new reporter molecules able to integrate into cellular glycans, synthetic analogues of GalNAc were prepared and tested as substrates of both enzymes acting sequentially in the GalNAc salvage pathway, galactokinase 2 (GK2) and uridylpyrophosphorylase AGX1. Detailed in vitro assays identified the GalNAc analogues that can be transformed into sugar nucleotides and revealed several bottlenecks in the pathway: a modification on C6 is not tolerated by GK2; AGX1 can use all products of GK2 although with various efficiencies; and all analogues transformed into UDP-GalNAc analogues except those with alterations on C4 are substrates for the polypeptide GalNAc transferase T1. Besides, all analogues that could be incorporated in vitro into O-glycans were also integrated into cellular O-glycans as attested by their detection on the cell surface of CHO-ldlD cells. Altogether our results show that GalNAc analogues can help to better define structural requirements of the donor substrates for the enzymes involved in GalNAc metabolism, and those that are incorporated into cells will prove valuable for the development of novel diagnostic and therapeutic tools.
Haloacetamido Analogues of 2-Amino-2-deoxy-D-mannose. Syntheses and Effects on Tumor-Bearing Mice
Fondy, Thomas P.,Emlich, Cheryl A.
, p. 848 - 852 (2007/10/02)
Haloacetamido analogues (fluoro, chloro, and bromo) of 2-deoxy-2-acetamido-D-mannose and their tetra-O-acetates were prepared from D-mannosamine hydrochloride, with either chloroacetic or bromoacetic anhydride or by dicyclohexylcarbodiimide-activated condensation with fluoroacetate followed by acetylation.Comparative specific rotations and (13)C and 1H NMR spectra were consistent with a β configuration for the tetra O-acetylated derivatives. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-(bromoacetamido)-β-D-mannose and the corresponding analogue of glucose inhibited thymidine incorporation into mouse L1210 leukemia cells by 50percent (IC50) at concentrations between 6 and 9 υM. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-(chloroacetamido-β-D-mannose was 3-fold more active in the thymidine-incorporation assay (143 +/- 24 υM, IC50) than was the corresponding analogue in the glucose series (425 +/- 62 υM; p = 0.005).All of the haloacetamido free sugars, as well as the tetra-O-acetates of the fluoroacetamido analogues in the glucose, galactose, and mannose series, were inactive in the thymidine incorporation assay at 1 mM.In the mannose series the tetra-O-acetylated chloroacetamido and bromoacetamido analogues, as well as the bromoacetamido free sugar, could be administered at relatively high in vivo tolerated doses compared to the corresponding analogues in the galactose and glucose series.These three mannose anlogues produced high proportions of cures of Ehrlich tumor-bearing B6D2F1 mice, whereas in the galactose and glucose series only the tetra-O-acetylated bromoacetamido analogues had previously produced in vivo chemotherapeutic activity.
