作者: M Pinkney , E Beachey , M Kehoe
DOI: 10.1128/IAI.57.8.2553-2558.1989
关键词: Site-directed mutagenesis 、 Cysteine 、 Biology 、 Biological activity 、 Escherichia coli 、 Biochemistry 、 Mutagenesis (molecular biology technique) 、 Mutant 、 Streptolysin 、 In vitro 、 Molecular biology
摘要: Site-directed mutagenesis of the TGC codon in a cloned streptolysin O (SLO) gene exchanged single Cys residue SLO for either Ala or Ser. The parent wild-type (SLO.Cys-530) and SLO.Ala-530 SLO.Ser-530 mutant toxins, expressed Escherichia coli, were purified analyzed. Wild-type SLO.Cys-530 showed no significant differences their specific hemolytic activities, while had reduced (ca. 25%), but still considerable, activity as compared with that SLO. toxins extracted from lysed erythrocyte membranes similar sedimentation profiles on sucrose density gradients, suggesting mutations did not affect ability to form oligomers membranes. These results show widely held assumption vitro cytolytic requires an essential is true.