Inhibition of Rat Liver Threonine Dehydratase by Tris(hydroxymethyl) aminomethane (Tris) and Reversal by Orthophosphate 1

Summary

A 55-fold purified rat liver threonine dehydratase in phosphate buffer was found to retain only 4% of the original activity after dialysis against Tris buffer at pH 8.3. Addition of pyridoxal phosphate (PLP) to the Tris-inactivated dehydratase restored 96% of the original activity; addition of orthophosphate restored 83% of the activity. The concentration of pyridoxal phosphate or orthophosphate required for reactivation approximated the free amine concentration of Tris at pH 8.3.