The mechanism of biosynthesis and direction of chain extension of a polyl-(N-acetylglucosamine 1-phosphate) from the walls of Staphylococcus lactis N.C.T.C. 2102

Abstract

1. The synthesis of a polymer of N-acetylglucosamine 1-phosphate, occurring in the walls of Staphylococcus lactis N.C.T.C. 2102, was examined by using cell-free enzyme preparations. The enzyme system was particulate, and probably represents fragmented cytoplasmic membrane. 2. Uridine diphosphate N-acetylglucosamine was the only substrate required for polymer synthesis and labelled substrate was used to show that N-acetylglucosamine 1-phosphate is transferred as an intact unit from substrate to polymer. 3. The properties of the enzyme system were studied. A high concentration of Mg2+ or Mn2+ was required for optimum activity, and the pH optimum was about 8·5. 4. End-group analysis during synthesis in vitro showed that newly formed chains contain up to about 15 repeating units. Pulse-labelling indicated that chain extension occurs by transfer from the nucleotide to the ‘sugar-end’ of the chain, i.e. to the end that is not attached to peptidoglycan in the wall.