Abchives of Biochemistry and Biophysics
نویسندگان
چکیده
Prephenate dehydrogenase of Pseudomonas aeruginosa is unstable in crude extracts or following its partial purification by gel-filtration. However, when ion-exchange chromatography (DEAE-cellulose) is the initial purification step, a stable enzyme preparation is recovered. The enzyme, having a molecular weight of approximately 150,000, has a K, for prephenate of 0.05 mM, and is inhibited competitively (with respect to prephenate) by L-tyrosine. Feedback inhibition has not been found previously. It is concluded that the entry of prephenate into the tyrosine pathway is regulated largely by L-phenylalanine acting upon a bifunctional enzyme complex bearing activities for chorismate mutase and prephenate dehydratase. Overproduction of L-tyrosine in uiuo is probably prevented by feedback inhibition of prephenate dehydrogenase.
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