Heme Peroxidase Polypeptides

An isolated polypeptide comprises an amino acid sequence of SEQUENCE ID NO: 1, or a chemically active variant thereof, wherein the polypeptide comprises a mutation selected from the group comprising: TIlOV; K232F/N; and K241F/N. Also described is a method of generating a heme peroxidase protein suitable for immobilisation to a support that comprises the step of introducing a reactive residue into the protein at at least one tethering position in the protein. The tethering position is sufficiently distant from the active site of the protein such that, when the protein is immobilised to the support through the at least one reactive residue, the protein is oriented with the active site substantially facing away from the support. When the protein is horseradish peroxidise, the tethering position is selected from the group comprising: R118; R159; and R283. Also provided is an isolated polypeptide comprising an amino acid sequence of SEQUENCE ID NO: 1, or a biologically active fragment or variant thereof, wherein at least one of the arginine residues located at positions 118, 159, and 283 is replaced with a reactive residue.