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BY-NC-ND 3.0 license Open Access Published by De Gruyter June 2, 2014

Porin of Rhodobacter capsulatus: Biochemical and Functional Characterization

  • Daniela Woitzik , Jürgen Weckesser , Roland Benz , Stefan Stevanovic , Günther Jung and Jürg P. Rosenbusch

Abstract

The major outer membrane protein of Rhodobacter capsulatus 37 b4 (capsule-free) was iso­lated. Strong porin-activity was observed after reconstitution into artificial lipid bilayer mem­branes with a single channel conductance of 3.15 nS in Im KC1. The porin migrated as a broad, single band (Mr above 90,000) on sodium dodecyl sulfate polyacrylamide gel electro­ phoresis and dissociated into a single species of polypeptides (Mr 36,000) on treatment with EDTA (10 mM at 30 °C, 20 min) or by heating (100 °C, 5 min). Analytical ultracentrifugation studies demonstrated the native porin to be a trimer. The monomers chromatofocused as a single, sharp peak on fast performance liquid chromatography and only one band, corre­ sponding to an isoelectric point of about 4.0, was obtained on isoelectric focusing. Gas-phase sequencing of the 23 N-terminal residues revealed Glu-Val-Lys-Leu-Ser-Gly-Asp-Ala-Arg-Met-Gly-Val-Met-Tyr-Asn-Gly-Asp-Asp-X-Asn-Phe-Ser-Ser.

Received: 1990-2-19
Published Online: 2014-6-2
Published in Print: 1990-6-1

© 1946 – 2014: Verlag der Zeitschrift für Naturforschung

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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