TABLE 2

Kinetic parameters for bovine XO metabolism of 6-substituted quinazolinones

R =KMaVmaxbV/KcKIEd
μ Mnmol/s/mg enzyme
OCH3859101N.D.
CH35612121615.2
H3117548N.D.
Cl1116414,9093.0
• N.D., not determined.

• a The concentration at half-maximal velocity. Errors are approximately 10% for each value.

• b The maximum velocity estimated from the asymptote for the hyperbola. Errors are approximately 10% for each value.

• c V/K multiplied by 1000.

• d The isotope effect on V/K determined by taking the ratio of V/K for the proton/deuterium substitution at the site of oxidation from Skibo et al. (1987).