Recombinant bovine lactoperoxidase as a tool to study the heme environmentin mammalian peroxidases

The cDNA encoding bovine lactoperoxidase (LPO) has been expressed in CHO ce lls. The recombinant LPO mas secreted as an enzymatically active single cha in molecule presenting two immunoreactive forms of 88 kDa and 82 kDa, diffe ring by their glycosylation. rLPO exhibited the characteristic absorbance s pectrum with a Soret peak at 413 nm, Engineering of rLPO into a myeloperoxi dase (MPO)-like molecule was attempted by substituting Gln-376 by Met, a re sidue known to achieve covalent binding with the heme in MPO. However, the resulting bovine LPO mutant failed to acquire the peculiar absorbance spect rum and the chlorinating activity of MPO, underlining the complex nature of interactions in the heme vicinity, (C) 1998 Federation of European Biochem ical Societies.