Abstract
Effects of Peroxide, Catalase, and Hematin in the Assay of Liver Tryptophan Pyrrolase
Highlights
The lag phase of the reaction was similar to that noted in the same kind of preparation by Fcigclson and Greengard (I), it was not eliminated by hcmatin addit)ion as described by them, and not eliminated by reduction plus hematin
The fraction of the total activity referable to the apoenzyme (E) was calculated from the extra activity produced by hematin addition in the presence of reducing agent (Table I, Columns 4 - 3); the ferriporphyrin enzyme (EH+3) from the extra activity upon addition of a reducing agent (Table I, Column 3); and the ferroporphyrin enzyme from the activity without addition (Table I, Column 1)
Rat and mouse liver preparations varying lo-fold in t,heir catalase activities (0.58 to 5.72 k) and in their optimal amounts of glucose oxidase required (0.84 to 9.7 units) all showed tryptophan pyrrolase reaction rates that rose and fell as more glucose oxidase was added
Summary
C57BL strains weighing 30 to 40 g were used. Rats used for induction of the tryptophan pyrrolase were given 50 mg of L-. The resulting supernatant solutions were used within 5 hours after preparation for the tryptophan pyrrolase assay or for preparation of the pH 5.4 precipitated fraction. For the latter, an aliquot at 0” was adjusted to pH 5.4 with about 0.02 vohrme of. The tryptophan pyrrolase activity, cspressed as micromoles of kynurenine formed in an hour per ml of enzyme or g of liver, was determined from t,he linear portion of the rate curves. Projertion of this linear portion of the curve onto the time axis provided the measure of the lag phase of the reaction (the period from zero time until the reaction reached its full rate). The catalasc activities given are the total amounts present in the assay mixtures
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