Novel bacterial peroxidase without catalase activity from Flavobacterium meningosepticum:: purification and characterization

A novel bacterial peroxidase co-produced intracellularly with H2O2-forming nucleoside oxidase, was purified from the cell-free extract of Flavobacterium meningosepticum to homogeneity with 10.3% overall recovery through simple purification procedures including successive DEAE-Sephacel, phenyl-Sepharose CL-4B and Sephacryl S-300 chromatography. The relative molecular mass of the native enzyme was 220 000 Da, and that of its subunit was 54 000 Da. In contrast to other major intercellular peroxidases of bacterial origin, the enzyme did not show any catalase activity. The amino acid sequences of the 92 NH2-terminal amino acids and three internal peptides showed no significant homology with known peroxidases. The enzyme was not sensitive to the typical peroxidase inhibitors NaCN, NaF and NaN3, while mercuric ion strongly inhibited the enzyme activity, and some carbonyl reagents were also found to have inhibitory effects. The enzyme showed a small K-m value for H2O2 (9.5 mu M) compared to other peroxidases. On the basis of its visible absorption spectrum, the enzyme contained about 1.3 mol of heme per molecule. (C) 1999 Elsevier Science B.V. All rights reserved.