On the Evolution of an Oligocephalic Enzyme. Glutamine- Chorismate-Amidotransferase-Free Anthranilate Phosphoribosyltransferases from Mutant Strains of Salmonella typhimurium

Abstract

A procedure was described for the purification of 2 glutamine-chorismate-amido-transferase-free anthranilate phosphoribosyltransferases [EC 2.4.2.18] from mutant strains TAX6trpR782 and trpAB1653trpR782 of S. typhimurium. The native enzymes tend to aggregate forming polymers of MW 333,000 in the case of TAXtrpR782 and 220,000 and larger than 1 .times. 106 in the case of trpAB1653trpR782. In the presence of sodium dodecyl sulfate the polymer of trpAB1653trpR782 dissociates into a single component with MW of 72,000. Unlike anthranilate phosphoribosyltransferase of the wild type component II, the glutamine-chorismate-amidotransferase-free proteins do not complex with component I. They do show catalytical similarities with the wild type with respect to anthranilate phosphoribosyl-transferase activity.