Abstract: | A modification of the resorcinol method of Kulka1 for the determination of ketoses is described. Though being a stopped enzyme test, it is much more sensitive than the carbazol method and by applying microtiter plates and measuring with an ELISA reader, a large number of tests can be performed within a short time, thereby facilitating initial velocity studies. The test is linear up to a concentration of 2.5 m
-xylulose even in the presence of 10 m
-xylose and 2 m
-fructose in the presence of 10 m
-glucose. The sensitivity is 25 μ
for xylulose and 38 μ
for fructose. The test method is insensitive to perturbations of substances frequently used in isolation procedures such as ammonium sulfate, Triton X-100, PEG 6000, sodium dodecyl sulfate, and ethanol in moderate concentrations. |