Characterization of recombinant bovine lactoperoxidase produced by CHO cells.

A full length cDNA coding for bovine lactoperoxidase (bLPO) was amplified by RT-PCR from mRNA extracted from mammary gland cells. The recombinant DNA was introduced into Chinese Hamster Ovary (CHO) cells by the electroporation method. The recombinant bovine lactoperoxidase (rbLPO) expressed in a large- scale production system was purified by a combination of anion- exchange chromatography and cation- exchange chromatography. The purified rbLPO was then characterized in terms of molecular weight, N- terminal amino acid sequence, carbohydrate structure, peroxidase activity, and spectroscopic properties. The data showed that rbLPO is secreted as a single chain molecule, as two major forms differing in glycosylation. The N- terminal amino acid of rbLPO was Asp101, starting 19 residues upstream from the N- terminus of natural bovine lactoperoxidase (nbLPO). The rbLPO is enzymatically active and its specific absorption spectrum at 413 nm appears to be identical to that of LPO. This indicates that heme is integrated into the recombinant protein. The properties of rbLPO are discussed as compared to the nbLPO expressed in CHO cells obtained previously.