Open AccessBiomimetic constructs. De‐novo design of redox proteins
Author(s) -
Rau Harald K.,
Haehnel Wolfgang
Publication year - 1996
Publication title -
berichte der bunsengesellschaft für physikalische chemie
Language(s) - English
Resource type - Journals
ISSN - 0005-9021
DOI - 10.1002/bbpc.19961001222
Subject(s) - antiparallel (mathematics) , heme , chemistry , hemeprotein , protein design , circular dichroism , stereochemistry , transmembrane protein , cofactor , crystallography , protein structure , biochemistry , enzyme , physics , receptor , quantum mechanics , magnetic field
A modular strategy for the de‐novo synthesis of four‐helix bundle proteins has been established. The individual helices and a cyclic decapeptide are purified to homogeneity after deprotection before they are coupled chemo‐ and regioselectively in predetermined orientations. The orientation of the helices relative to each other as well as of the N‐terminus is controlled by different side chain protecting groups. The new protein adapts the predicted structure of the heme binding core of the transmembrane cytochrome b to a soluble form. This protein with a molecular mass of 14,293 with antiparallel orientation of the four helices binds two heme groups in its hydrophobic interior via four histidines. Circular dichroism studies indicate a high helical content of the complex and a free energy of folding of −30.4kJ/mol. The two heme groups have midpoint potentials of −106 and −170 mV, respectively. The modular design of the de‐novo protein can easily be modified and provides the basis for detailed physical studies of molecular parameters.