• vinyl orientation;
  • electronic conjugation;
  • peroxidase;
  • crystallography


A direct relationship between the νmath image and Cb atoms of the vinyl groups and the surrounding atoms, the origin of the different vinyl orientations is ascribed to a variety of interactions, namely van der Waals contacts, weak π–π electron interactions and C—H···O hydrogen bonds. The vinyl group orientations appear to depend on the concerted orientations of the distal helix B and proximal helix F axes as controlled by the H-bonds between the distal Arg, a heme propionyl group and a residue on the extended strand adjacent to proximal helix F. Finally, a possible mechanism explaining the alkaline configuration changes of cytochrome c peroxidase and the reorientation of a vinyl group upon fluoride complexation is given. Copyright © 2003 John Wiley & Sons, Ltd.