Some Characteristics of Ureaplasma urealyticum. Urease Activity in a Simple Buffer: Effect of Metal Ions and Sulphydryl Inhibitors

Abstract

Urealytic activity of the cytoplasmic fraction of U. urealyticum prepared by digitonin lysis was assayed in a simple buffer system (HEPES [2-[-4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid] plus EDTA) by measuring the release of 14CO2 from [14C]urea. The Km of this preparation agreed with previous observations of the same activity measured in a more complex reaction mixture. The substrate concentration at which maximum velocity occurred was approximately 20 mM. The activity was sensitive to heavy metals and inhibitors which react with SH groups such as N-ethylmaleimide and p-chloromercuribenzoate. It was not inhibited by Ca2+ or Mg2+ or by the reaction products, NH3 and CO2.