ON LOCALIZATION OF ALKALINE PHOSPHATASE AND CYCLIC PHOSPHODIESTERASE IN ESCHERICHIA COLI

Evidence is presented for the view that alkaline phosphatase, acid phosphatase, and cyclic phosphodiesterase are localized near the surface of Escherichia coli, external to the protoplasmic membrane. Phosphate esters which do not penetrate E. coli can be hydrolyzed by intact cells, suggesting that these enzymes are outside of the permeability barrier for phosphate esters. However, the per cent of total activity expressed by intact cells (compared with equivalent cell extracts) varies over extremely wide limits, depending upon the substrate and its concentration. It is believed that components of the cell wall are interposed between the enzymes and the external medium. Presumably the different phosphate esters vary in ease of penetration of the wall barrier. A modified procedure for the purification of E. coli alkaline phosphatase is also presented. © 1968, American Chemical Society. All rights reserved.