KINETICS OF NITROSATION OF THIOPROLINE, THE PRECURSOR OF A MAJOR NITROSO COMPOUND IN HUMAN-URINE, AND ITS ROLE AS A NITRITE SCAVENGER

  • 1 January 1984
    • journal article
    • research article
    • Vol. 75  (10) , 889-894
Abstract
The kinetics of nitrosation of thioproline was studied. The rate of the reaction increased with decrease in pH, and was 1st-order with respect to nitrite concentration. The reaction rate was proportional to the concentration of total thioproline (free plus protonated), not to that of free thioproline. The initial reaction rate followed the equation: rate = k4 .times. [thioproline] .times. [NaNO2] .times. [H+]. The rate constant was 0.494 M .cntdot. at pH 2.0 and 37.degree. C Thioproline acted as a nitrite scavenger and suppressed the formation of a carcinogen, N-nitroso-N-benzylmethylamine, from N-benzylmethylamine and nitrite. More than 90% of the formation of N-nitroso-N-benzylmethylamine was inhibited by adding 20 mM thioproline to a reaction mixture containing 20 mM N-benzylmethylamine and 20 mM sodium nitrite at pH 3.0 and 37.degree. C.