title: Initial membrane reaction in the biosynthesis of peptidoglycan. Spin-labeled intermediates as receptors for vancomycin and ristocetin.
abstract: Phospho-N-acetylmuramyl-pentapeptide translocase (UDP-MurNAc-Ala-DGlu-Lys-DAla-DAla:undecaprenyl phosphate, phospho-MurNAc-pentapeptide transferase) catalyzes the initial membrane reaction in the biosynthesis of peptidoglycan. The spin-labeled nucleotide, UDP-MurNAc-Ala-DGlu-Lys (Nepsilon-2,2,5,5-tetramethyl-N-oxyl-pyrroline-3-carbonyl)-DAla-DAla, was used as a substrate by this enzyme for the synthesis of membrane-associated undecaprenyl-diphosphate-MurNAc-Ala-DGlu-Lys(Nepsilon-Tempyo)-DAla-DAla. The spin-labeled substrate and product complex with the antibiotics vancomycin and ristocetin. The association constants for the spin-labeled nucleotide are 6.2 times 10(5) and 6.2 times 10(4) M-1 for vancomycin and ristocetin, respectively. The association constants for the spin-labeled lipid intermediate are 3.0 times 10(4) and 2.1 times 10(4) M-1 for vancomycin and ristocetin, respectively. These results indicate that the acyl-DAla termini of membranes-associated spin-labeled undecaprenyl-diphosphate-MurNAc-pentapeptide are accessible to vancomycin and ristocetin and that the association constants are smaller than those determined for the corresponding antibiotic spin-labeled UDP-MurNAc-pentapeptide complexes.
mesh_terms: D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism*; D002848:Chromatography, DEAE-Cellulose; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D008433:Mathematics; D008968:Molecular Conformation; D009112:Muramic Acids / Q000032:analysis; D009842:Oligopeptides; D010457:Peptidoglycan / Q000096:biosynthesis* / Q000302:isolation & purification; D011485:Protein Binding; D011487:Protein Conformation; D011955:Receptors, Drug; D012310:Ristocetin / Q000494:pharmacology*; D013113:Spin Labels; D013210:Staphylococcus / Q000378:metabolism*; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D009112:Muramic Acids; D009842:Oligopeptides; D010457:Peptidoglycan; D011955:Receptors, Drug; D013113:Spin Labels; D012310:Ristocetin; D014640:Vancomycin