The Release of Enzymes by Osmotic Shock from Escherichia coli in Exponential Phase

Abstract

A number of degradative enzymes are specifically released from exponentially growing Escherichia coli by osmotic shock.They include alkaline phosphatase, cyclic phosphodiesterase, 5'-nucleotidase, acid phosphatase, and the ribonucleic acidinhibited endonuclease that is active with deoxyribonucleic acid.Small amounts of RNase are also set free, but some 16 control enzymes are found to remain within the cell.Only about 4% of the cellular protein is released into the shock medium.The procedure for osmotic shock has been modified in order to obtain about 80% viability with exponential cells, with good release of enzymes.In the first stage, cells are exposed to 20% sucrose-1 X 10 -4 M EDTA.In the second stage, the pellet of sucrose-treated cells is rapidly dispersed in cold 5 X 10 -4 M MgC 1 2, which causes the enzymes to be liberated.At least 90% of the DNA endonuclease and 50% of the latent ribonuclease are released from exponentially growing E. coli when as much as 2 X 10 -2 M MgC1 2 is used in the procedure for osmotic shock.