EFFECT OF CAPRYLOHYDROXAMIC ACID ON RUMINAL UREASE

A cell-free extract was prepared from the rumen fluid by ultracentrifugationt afterultrasonic treatment. It was used as an enzyme specimen for the enzymic experiment.It was found that ruminal urease had some similar properties to those of plant urease.The Km value of ruminal urease was 6.3 X 10 3 M, wlaich was in the same order as thatof plant urease. The inhibitory effect of caprylohydroxamic acid (CHA) was enltancedpromptly in the concentration of 1 X NO 4 M in both cell-free extract and rumen fluid, whereas it was very slight in the concentration of J X 10 5 to 1 X IQ IVI.When the velocity was plotted against the substrate concentration, instead of simplehyperbolic saturatiort curve obtained in the presence of the substrate alon, a sigmoidsaturatioua curve was obtained. At low substrate concentrations, tlae reaction was slowedconsiderably. Tlne higher the substrate concentration, tlae lower became the effect ofCHA, and a pattern of noncompetitive inhibition was shown.CHA was investigated for effect on rumen fermentation. Neither prodructioru ofvolatile fatty acids nor pH was affected in tlae culture medium by addition of CHA, butthe decomposition of urea accompanied by production of amrr.onia was affected signifi-cantly by the added CHA until 3 hours of incubation.In conclusion, CHA was expected to be applicable to the rtuminant fed a rationcontaining urea.