INCORPORATION OF 2-FLUOROHISTIDINE IN MURINE PROTEIN INVIVO

The tissue distribution an time course of incorporation into acid insoluble (bound) and acid soluble (free) fractions of [H-3]2-fluorohistidine is compared to that of U[C-14]Histidine in mouse tissues in vivo. The cycloheximide-sensitive incorporation of 2-FHis is between 9 and 17 percent of that of His. Unlike [C-14]His a major fraction, approximately 90% at 72 hrs, of isotope derived from [H-3]2-FHis remains in tissues for a prolonged period in an acid soluble form. The excretion of isotope derived from [C-14]His (T1/2 = 5 hr) is more rapid than from [H-3]2-FHis (T1/2 = 11.4 hrs). 2-FHis, at doses from 100 to 250 mg/kg produce a reversible inhibition of growth in mice.