Specificity of GDP‐Man:dolichyl‐phosphate mannosyltransferase for the guanosine diphosphate esters of mannose analogues containing deoxy and deoxyfluoro substituents

Abstract

Guanosine diphosphate (GDP) esters of 2-deoxy-D-glucose (2dG lc), 2-deoxy-2-fluoro-D-mannose (2FMan), 3-deoxy-Dmannose (3dMan), 4-deoxy-D-mannose (4dMan) and 6-deoxy-D-mannose (6dMan) have been synthesised and tested for their ability to act as inhibitors of dolichyl phosphate mannose synthesis (enzyme: GDP-mannose:dolichyl-phosphate mannosyltransferase, EC 2.4.1.83) in chick embryo cell microsomal membranes. The following order of efficiency was found with the apparent Ki in parentheses: GDP-6dMan (0.40/zM + 0.15) > GDP-3dMan (1.0 gM + 0.1) = GDP-2dGIc (1.3/zM+0.2) > GDP-4dMan (3.1/zM+0.1) GDP-2FMan (15 gM+0). For comparison the Km for GDP-Man was 0.52/zM + 0.02 and the Ki for GDP was 56/~M _+ 2. These results indicate that the 6-hydroxyl group of mannose is not crucial for emzyme-substrate recognition, whereas the 2-and 3-hydroxyls may have some involvement. The 4-hydroxyl appears to be an important determinant for enzyme-substrate recognition in this mannosyltransferase.

Metabolic Pathways of Leishmania Parasite: Source of Pertinent Drug Targets and Potent Drug Candidates

“…In parasitic protozoa, the lipopeptide antibiotic amphomycin forms a compound with Dol-P (mannose donor) in the presence of Ca2 + , limiting GPI production in vitro by blocking the interaction between the Dol-P-Man synthase and Dol-P [65]. In vivo, synthetic mannosides acceptor substrates (thiooctyl-and octyl a-mannosides) and Mannose analogues, 2deoxy-2-fluoro-D-glucose (2FGlc) and 2-deoxy-D-glucose (2dGlc), have been shown to impede Dol-P-Man synthesis [66]. N-4-(-5(trifluromethyl)-1-methyl-1H benzo[d]imidazole-2 yl) phenyl) was docked to GPI14 in eight different ways.…”

Mannosyltransferases

“…The specificity seems to be for the GDP moiety, for in vitro, some Man-T can use GDPMan analogs in which the mannose has been modified or replaced with another sugar [20]. The ability of Man-T to recognize analogs of GDPMan has been exploited for photoaffinity labeling of Man-T with GDP-he~anolamine-'~~ Iazidosalicylic acid [21].…”

Metabolic Pathways of Leishmania Parasite: Source of Pertinent Drug Targets and Potent Drug Candidates

“…14, x FOR PEER REVIEW 8 of 26protozoa, the lipopeptide antibiotic amphomycin forms a compound with Dol-P (mannose donor) in the presence of Ca 2+ , limiting GPI production in vitro by blocking the interaction between the Dol-P-Man synthase and Dol-P[67]. In vivo, synthetic mannosides acceptor substrates (thiooctyl-and octyl a-mannosides) and Mannose analogues, 2-deoxy-2-fluoro-D-glucose (2FGlc) and 2-deoxy-D-glucose (2dGlc), have been shown to impede Dol-P-Man synthesis[68]. N-4-(-5(trifluromethyl)-1-methyl-1H benzo (d)imidazole-2 yl) phenyl) was docked to GPI14 in eight different ways.…”