No abstract

The initial reaction in the biosynthesis of peptidogiycan is catalyzed by phospho-A^-acetylmuramyl-pentapeptide translocase (UDP-MurNAc-L-Ala-D-7-Glu-L-Lys-D-Ala-o-Ala: C56-isoprenoid alcohol phosphate phospho-MurNAc-pentapeptide transferase). In addition to the transfer reaction, the enzyme catalyzes the exchange of [8H]uridine monophosphate with the uridine monophosphate moiety of UDP-MurNAc-pentapeptide. In addition to an absolute requirement for Mg2+, the translocase is stimulated by either K+, NH4+, Rb+, or Cs+. Addition of K+ (0.17 m) to dialyzed membranes stimulates the exchange reaction 20-fold and the transfer reaction 2-fold. The stimulation by K+ gives a normal hyperbolic saturation curve with a Michaelis-Menten constant of 0.01 m in the exchange reaction. The value for (1) established from Hill plots suggests the absence of homotropic effects and that a single binding site for K+ exists in T Xhe biosynthesis of peptidoglycan, the major structura' heteropolymer of bacterial cell walls, is catalyzed by a series of enzymes associated with the bacterial membrane (Anderson