Solubilization of Valine-sensitive Acetohydroxy Acid Synthetase from Neurospora Mitochondria

Abstract

Acetohydroxy acid synthetase [EC 4.1.3.18] of Neurospora crassa has been solubilized from a mitochondria) pellet fraction by sonic treatment in 1.0M potassium phosphate buffer at pH 7.5 containing 10mM MgSO₄ and centrifugation at 180, 000×g for 20 min. The soluble enzyme thus obtained has a high specific activity and a high sensitivity to valine comparable to the original mitochondria) pellet suspension when the activity was determined in high concentrations of potassium phosphate.