Amphitrite ornata dehaloperoxidase: enhanced activity for the catalytically active globin using MCPBA.
Dehaloperoxidase (DHP) from Amphitrite ornata is the only heme-containing, hydrogen peroxide-dependent globin capable of oxidatively dehalogenating halophenols to yield the corresponding quinones. To ascertain that this enzymatic activity is intrinsic to DHP, we have cloned and expressed the enzyme in Escherichia coli. We also find that an alternate oxygen atom donor, meta-chloroperbenzoic acid, gives appreciably higher activity than hydrogen peroxide. Under optimal turnover conditions (large peroxide/peracid excess), after an initial burst of activity, DHP appears to become trapped in a non-catalytic state (possibly Compound II) and is unable to fully convert all halophenol to product. However, full substrate conversion can be achieved under more physiological conditions involving a much smaller excess of oxygen atom donor. Parallel studies have been carried out using horseradish peroxidase and myoglobin to calibrate the activity of DHP versus typical peroxidase and globin proteins, respectively.
Osborne
Robert L
RL
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
Taylor
Laurie O
LO
Han
Kai Ping
KP
Ely
Bert
B
Dawson
John H
JH
D000818:Animals; D002384:Catalysis; D002723:Chlorobenzoates / Q000737:chemistry*; D005914:Globins / Q000378:metabolism*; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism*; D011077:Polychaeta / Q000201:enzymology*; D013056:Spectrophotometry, Ultraviolet
D002723:Chlorobenzoates; D005914:Globins; D010544:Peroxidases; C000433:3-chloroperbenzoic acid