Characterization of the Major Envelope Protein from Escherichia coli

摘要: The major envelope protein from Escherichia coli has been purified by differential heat extraction in dodecyl sulfate and subsequently freed of the detergent. polypeptide is homogeneous a mass 36,500 daltons. Homogeneity based on four criteria, three which are independent its behavior detergents. Its molecular weight was established methods binding agrees with that derived mobility band observed standard gel electrophoretic analysis unfractionated cell envelopes after treatment at 100°. accounted for entirely, or nearly constituent amino acids. These results imply bound amounts corresponding to those found most polypeptides. also isolated association rigid layer 2 % 60°. This complex composed about 65 protein, remaining being largely peptidoglycan-lipoprotein structure. In this form completely resistant trypsin, but upon dissociation it quickly degraded small fragments. Unlike dissociated polypeptide, complexed does not bind tightly even prolonged exposure high excess A large fraction exists as β-structure, determined circular dichroism infrared spectroscopy. 105 copies per arranged lattice structure hexagonal symmetry periodicity 7.5 nm outer face peptidoglycan. regular array appears be closely related quaternary vivo. All strains E. tested contain protein.