Crystallographic and Solution Studies on Phosphoserine Aminotransferase (PSAT) from E.coli

Summary

Phosphoserine aminotransferase from E.coli has been crystallized in space group P2₁2₁2₁, with one ∝₂ dimeric molecule per asymmetric unit. Single crystal microspectrophotometric measurements have shown that the enzyme is catalytically active in the crystal. X-Ray data for the native form and 2 heavy atom derivatives have been collected on a CAD4-di f fractometer. A 6Å resolution Fourier-map has been calculated? interpretation is underway. The orientation of the noncrystallographic two-fold axis of the dimer has been determined. Solution studies have shown that the activity maximum is below the pK of the internal aldimine. The quaternary and secondary structure have been determined by analytical ultracentrifugation and CD measurements.