Purification of aspartate transcarbamoylase from Pseudomonas syringae.

The aspartate transcarbamoylase (ATCase) from Pseudomonas syringae has been purified. The purified enzyme was shown by SDS-PAGE to give two bands. Unambiguous results from N-terminal sequencing suggested that each band represented a homogeneous polypeptide. The M(r) (relative molecular mass) of the polypeptides was estimated to be 47 kDa and 34 kDa. The M(r) of the holoenzyme determined by gel filtration and electrophoretic migration in polyacrylamide gradient gels under non-denaturing conditions was estimated at approximately 490 kDa. These findings suggest a subunit structure different from any previously described for a bacterial ATCase.