- Site-directed mutagenesis of coumarin-type anticoagulant-sensitive VKORC1: evidence that highly conserved amino acids define structural requirements for enzymatic activity and inhibition by warfarin. Rost, S., Fregin, A., Hünerberg, M., Bevans, C.G., Müller, C.R., Oldenburg, J. Thromb. Haemost. (2005)