Secondary structure of a channel-forming protein: porin from E. coli outer membranes.

Open Access
Publisher Website
Google Scholar
Abstract
Porin from Escherichia coli outer membranes has been analysed by high angle diffuse X‐ray diffraction, and by attenuated total reflection infrared spectroscopy. These methods demonstrate independently that the majority of the polypeptide backbone is arranged in anti‐parallel beta‐pleated sheet structure. The average length of the beta‐strands, which are oriented nearly normal to the membrane plane, is estimated to be 10‐12 residues, independent of the method used. Although the details of strand arrangement (beta‐barrels or stacked sheets) are not as yet known, porin represents the first transmembrane protein for which beta‐structure has been established unequivocally.