Bojanowski, R. (University of Illinois, Urbana), Elizabeth Gaudy, R. C. Valentine, and R. S. Wolfe. Oxamic transcarbamylase of Streptococcus allantoicus. J. Bacteriol. 87:75-80. 1964.-An improved colorimetric assay for carbamyl oxamate, which allows the precise measurement of the activity of oxamic transcarbamylase, has been developed. Activity is maximum over the pH range from 8.3 to 8.7. A cation requirement is satisfied by 2.5 x 10(-3)m Mg(++) or Mn(++). The equilibrium constant for the phosphorolysis of carbamyl oxamic acid is 1.6, corresponding to a negative free energy change of -285 cal per mole.