A sensitive radiometric assay for tryptophan hydroxylase applicable to crude extracts.
We describe here a simple and convenient method for assay of tryptophan 5-monooxygenase (hydroxylase), applicable to enzyme in all states of purification. It is based on the enzyme-catalysed formation of 5-hydroxy-[4-3H]tryptophan from [5-3H]tryptophan, and the subsequent acid-dependent quantitative release of 3H as 3H2O; unreacted substrate is removed with activated charcoal. The assay is linear with respect to both protein concentration and time, and gives results similar to those in a standard fluorimetric assay.
D006916:5-Hydroxytryptophan / Q000378:metabolism; D000818:Animals; D008722:Methods; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014365:Tryptophan Hydroxylase / Q000032:analysis*
D006916:5-Hydroxytryptophan; D014365:Tryptophan Hydroxylase