The purification of Neurospora crassa myo-inositol-1-phosphate synthase (EC 126.96.36.199) was studied by affinity chromatography using the substrate (glucose-6-phosphate), the inhibitor (pyrophosphate), the coenzyme (NAD+) and the coenzyme analogues (5'AMP and Cibacron Blue F3G-A) of the enzyme as adsorbents attached to agarose gel. Myo-inositol-1-phosphate synthase could be separated completely from the contaminating substance, glucose-6- phosphate dehydrogenase (EC 188.8.131.52), on Blue Sepharose CL-613 and on pyrophosphate-Sepharose. The purified enzyme had a specific activity of 16 400 U/mg. The sodium dodecyl sulfate/polyacrylamide gel electrophoresis of 60 pg of this purified enzyme gave a homogenous band. The enzyme was found to be composed of four identical subunits having a molecular weight of 65 000.
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