Heat-labile enterotoxin of Escherichia coli. Characterization of different crystal forms.

摘要: Heat-labile enterotoxin (LT) was obtained in large quantities (several-gram amounts) and great purity from Escherichia coli C600 carrying the LT-coding multicopy plasmid EWD299. By growing this strain on a medium that allows high cell densities early stationary phase, we increased net LT production per milliliter by factor of 200, compared to natural porcine enterotoxigenic E. coli. Adsorption redesorption Controlled-Pore Glass usually resulted 50-100-fold purification one simple step, which followed established procedures. shows tendency form crystals, which, however, are disordered. After numerous trials, conditions were found virtually eliminated disorder. Much better crystals employing CdCl2 KF as coprecipitating agents. yielded did not contain A subunits judged electrophoresis dissolved crystals. Adding results beautifully shaped diffracted beyond 2 suitable for resolution structure determination.