PHOSPHOTRANSACETYLASE OF ESCHERICHIA-COLI-B, PURIFICATION AND PROPERTIES

1. 1.|Phosphotransacetylase of Escherichia coli B has been purified 610 times over the crude extracts with 11% recovery, with the use of ammonium sulfate as a stabilizer. The purified enzyme was homogeneous in ultracentrifugal analysis with a s20,w of 8.1, and molecular weight has been tentatively estimated from the s value and from Sephadex G-200 gel filtration to be 1.6·105-2.5·105. 2. 2.|Km values of this enzyme were 3·10-3-4·10-3 M for acetyl phosphate and 3.2·10-4 M for CoA. 3. 3.|The enzyme was easily inactivated by dilution at 0° and by heat treatment at 46°, while sulfate protected the enzyme completely against both inactivations. The mechanism of action of sulfate as a stabilizer has been discussed in comparison with the action of phosphate. 4. 4.|Several differences in properties have been found between the enzyme of E. coli B and that of Clostridium kluyveri. These involve molecular weight and Km values for acetyl phosphate and for CoA. There was no difference between these two enzymes with respect to their stabilities in the presence and the absence of ammonium sulfate. © 1969.