H. Kuusk et al., Purification and characterization of a novel bromoperoxidase-catalase isolated from bacteria found in recycled pulp white water, ENZYME MICR, 28(7-8), 2001, pp. 617-624
A bacterial strain, Pseudomonad EF group 70B, containing a high catalase-li
ke activity was found in process water (white water) from pulp using recycl
ed fibers. The enzyme was purified and characterized, and found to be a hyd
roperoxidase. The active enzyme has an apparent molecular mass of about 153
kDa with two identical subunits and a pi value of 4.7. It has a rather sha
rp pH optimum for catalase activity at 6.0 hut exhibits catalase, peroxidas
e and brominating activities over a broad pH range from 4 to 8. It was not
inhibited by 3-amino-1,2,4-triazole. Peroxidase-like activity was found whe
n adding o-dianisidine, pyrogallol, guaiacol and 4-,aminoantipyrine. Bromin
ating activity was noticed using monochlorodimedone as a substrate. The abs
orption spectrum exhibited a Soret band at 403 nm. Upon reduction with dith
ionite the Soret peak decreased and shifted to 436 nm. Pyridine hemochrome
spectra indicated the presence of a protophorfyrin IX heme group and the en
zyme was inhibited by the known heme ligands cyanide and azide. N-terminal
amino acid analysis gave the sequence STEVKLPYAVAGSGTTILDAFPGE, which showe
d no homology with those of known catalases or peroxidases. It is concluded
that the enzyme is a novel type of catalase-peroxidase or, more specifical
ly, a bromoperoxidase-catalase : and that future developments of inhibitors
of hydrogen peroxide-degrading activities in white water may be based on t
his enzyme and other catalase-peroxidases, (C) 2001 Elsevier Science Inc. A
ll rights reserved.