Improved operational stability of chloroperoxidase through use of antioxidants.
Chloroperoxidase (CPO) from Caldariomyces fumago is a potentially very useful enzyme due to its ability to catalyze a large variety of stereoselective oxidation reactions, but poor operational stability is a main limitation for commercial use. In the present study, the possibility of increasing the operational stability by use of antioxidants was investigated using the oxidation of indole as model reaction. Caffeic acid was the antioxidant showing the strongest positive effects, reaching a total turnover number (TTN) of 135,000 at pH 4 and 4 mM hydrogen peroxide, compared to 28,700 in the absence of antioxidant. Portion-wise addition of hydrogen peroxide in the presence of caffeic acid caused a further increase in TTN to 171,000. An alternative way to reach high TTN was to use tert-butyl hydroperoxide as oxidant instead of hydrogen peroxide: a TTN of 600,000 was achieved although the reaction was quite slow. In this case, antioxidants did not have any positive effect. Possible mechanisms for the observed inactivation of CPO are discussed.
Grey
Carl Elovson
CE
Department of Biotechnology, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
Rundbäck
Fabian
F
Adlercreutz
Patrick
P
D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D002109:Caffeic Acids / Q000737:chemistry / Q000494:pharmacology; D002384:Catalysis / Q000187:drug effects; D002711:Chloride Peroxidase / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004795:Enzyme Stability / Q000187:drug effects; D005656:Fungal Proteins / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology; D007700:Kinetics; D003904:Mitosporic Fungi / Q000201:enzymology*; D015394:Molecular Structure; D016877:Oxidants / Q000737:chemistry / Q000494:pharmacology; D020122:tert-Butylhydroperoxide / Q000737:chemistry / Q000494:pharmacology
D000975:Antioxidants; D002109:Caffeic Acids; D005656:Fungal Proteins; D016877:Oxidants; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D002711:Chloride Peroxidase; C040048:caffeic acid