Escherichia coli 5'-nucleotidase: purification, properties and its release by osmotic shock

Escherichia coli 5'-nucleotidase was purified to apparent homogeneity as judged by polyacrylamide gel electrophoresis. Its molecular weight was estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, by gel exclusion chromatography, and by membrane filtration; values of 66 000, 48 500, and 15 000 to 30 000, respectively, were obtained. The enzyme was completely released from bacteria by osmotic shock treatment. The apparently anomalous behaviour of 5'-nucleotidase in terms of the molecular sieving hypothesis for the release of enzymes by osmotic shock proposed by Smith & Wyatt (1974) and extended by Broad & Smith (1979) is discussed.