title: Spring cabbage peroxidases--potential tool in biocatalysis and bioelectrocatalysis.
abstract: Two fractions of peroxidase activity, cationic Px-cat and anionic Px-ani, were isolated and partially purified (143.5- and 5.49-fold, respectively) from homogenate of spring cabbage heads. Optimum pH for both fractions is 6.0; however, Px-cat is almost equally active at neutral pH (7.0) while Px-ani reveals high activity in more acidic pHs (with 60% of maximum activity at pH 3.0). Optimal temperature for both fractions was 40 degrees C. Px-ani possessed much higher thermal stability at 40-50 degrees C (60% of remaining activity after 144h of incubation) than Px-cat. The peroxidases remained fully active during 4 weeks of storage at 4 degrees C. Kinetic studies revealed that Px-cat and Px-ani had lower apparent Km values for ABTS (0.0377 and 0.0625mM) and o-dianisidine (0.357 and 0.286mM) than for guaiacol (6.41 and 13.89mM). The best substrate for Px-cat was pyrogallol and for Px-ani-o-dianisidine. Px-cat immobilized on polyanionic PyBA-modified carbon electrode was found to produce linear repetitive signals upon consecutive additions of hydrogen peroxide during at least 1-week period and to work effectively under buffered and non-buffered conditions. These properties were comparable with those of commercially available horseradish peroxidase. Stability of the hybrid bioelectrocatalytic film and low costs of extraction and partial purification of Px-cat make it a highly promising enzyme for practical applications, including construction of bioelectrodes.
authors: Department of Biochemistry, Medical University of Lublin, Chodzki Street 1, 20-093 Lublin, Poland. anna.belcarz@am.lublin.pl
authors: Anna
authors: A
authors: Belcarz
authors: Grazyna
authors: G
authors: Ginalska
authors: Barbara
authors: B
authors: Kowalewska
authors: Pawel
authors: P
authors: Kulesza
mesh_terms: D001665:Binding Sites; D001937:Brassica / Q000201:enzymology*; D002384:Catalysis; D004563:Electrochemistry; D004789:Enzyme Activation; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010368:Pectins / Q000737:chemistry; D010544:Peroxidases / Q000737:chemistry* / Q000302:isolation & purification*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D010368:Pectins; D006861:Hydrogen Peroxide; D010544:Peroxidases; C003181:polygalacturonic acid