Substrate Binding of avian liver prenyltransferase.

摘要: Prenyltransferase (farnesyl pyrophosphate synthetase) was purified from avian liver and characterized by Sephadex sodium dodecyl sulfate gel chromatography, peptide mapping, end-group analysis. The enzyme is 85 800 +/- 4280 daltons consists of two identical subunits as judged electrophoresis, Chemical analysis the protein revealed no lipid or carbohydrate components. Avian prenyltransferase synthesizes farnesyl either dimethylallyl geranyl isopentenyl pyrophosphate. A lower rate geranylgeranyl synthesis also demonstrated. Michaelis constants for are 0.5 muM both V max reaction 1990 nmol min-1 mg-1 (170 mol mol-1 enzyme). Substrate inhibition evident at high low concentrations. 9 20 Vmax 16 (1.4 Two moles each allylic substrates bound per enzyme. apparent dissociation dimethylallyl, geranyl, pyrophosphates 1.8, 0.17, 0.73 muM, respectively. Dimethylallyl competitively to with one-for-one displacement. Four mole Citronellyl pyrophosphate, an analogue competitive binding 2 4 bound. data interpreted indicate that subunit has a single site accommodating pyrophosphates, one In absence analogue, can bind site.