The Dihydroxy Acid Dehydratase of Neurospora crassa

Abstract

Abstract The dihydroxy acid dehydratase of Neurospora crassa was purified 100- to 150-fold by fractionation with protamine sulfate, ammonium sulfate, Sephadex, and DEAE-Sephadex. It was found that the purified protein migrated in an electric field as a single band on acrylamide gel and in the analytical centrifuge. It had a lipid content of 44 to 50%. The enzyme activity was stabilized by the presence of magnesium ion. The Km values and pH optima were determined for both substrates, α,β-dihydroxyisovalerate and α,β-dihydroxy-β-methylvalerate.