N-Acetyl-muramyl-pentapeptides

Formation of the three-dimensional network of bacterial peptidoglycan includes synthesis both of glycosidic and peptide linkages, but only the former type of reaction is discussed in this Section. The assembly of the carbohydrate chains of a peptidoglycan has been shown to occur through a block mechanism. The initial reaction consists in transfer of N-acetyl-muramyl-pentapeptide phosphate from the corresponding UDP derivative... 

The next stage in peptidoglycan synthesis results from poly- merization of A-acetylglucosamine and N-acetyl muramyl-pentapeptide containing residues into peptidoglycan [ strands. The relevant reactions take place on the inner sur-i face of the plasma membrane (fig. 16.17). f In step 1 (see fig. 16.17), UDP-N-acetyl muramyl-... 

When UDP-2-acetamido-2-deoxy-D-glucose and UDP-N-acetyl-muramyl-pentapeptide are together added to broken bacterial-cell preparations, a new product is formed that contains the sugar and sugar-peptide portions of the precursors. If cells broken by means of a sonic oscillator are used, it is necessary to carry out the incubations on a filter-paper support " the precise function played by the filter paper is not yet known. In contrast, if enzymes are prepared by grinding cells with alumina, filter-paper support is unnecessary and the product contains a linear glycan backbone in which the two sugar residues occur in the alternate sequence expected. ... 

It was found that the first reaction in synthesis of linear peptido-glycan involves the transfer of pentapeptidyl-N-acetylmuramyl 1-phosphate to an endogenous, lipid acceptor from UDP-N-acetyl-muramyl-pentapeptide, with concomitant production of UMP (see Reaction I of Scheme 3). " This reaction is fully reversible, and its kinetics have been studied in detail. Evidence was presented that the glycosyl phosphate is attached to the lipid through a pyrophosphate bridge. Strominger and coworkers found that the endogenous, lipid acceptor could be extracted from the lyophilized. 

IV. Synthesis of N-acetyl-muramyl-tri-, tetra-, and -pentapeptides, and of Some... 

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