LAUSR

The interactive behaviour of an amphipathic peptide with the Cu2+ -, Ni2+ - and Zn2+ -complexes of 1,4-bis(triazacyclonon-1-yl)butane), bis(tacn)but , immobilised onto Sepharose CL-4B, has been investigated. The effects of incubation time, as well as the incubation buffer pH and ionic strength, have been examined. The binding data have been interrogated using Langmuir, Langmuir-Freundlich, bi-Langmuir and Temkin isothermal models and Scatchard plots. These results confirm that this amphipathic peptide binds with relatively high capacities to the immobilised Cu2+ - and Ni2+ -bis(tacn)but -Sepharose CL-4B sorbents via at least two discrete sites. However, the corresponding immobilised Zn2+ -sorbent had low binding capacity. Moreover, the magnitude of the binding capacities of these sorbents was dependent on the pH and ionic strength of the incubation buffer. These results are relevant to the isolation of E. coli expressed recombinant proteins that incorporate this and related amphipathic peptide tags, containing two or more histidine residues, located at the N- or C-terminus of the recombinant protein, and the co-purification of low abundance host cell proteins of diverse structure, by immobilised metal ion affinity chromatographic methods. This article is protected by copyright. All rights reserved.