Purification, characterization and kinetic properties of partially purified lipoxygenase, extracted from peanut seeds (Arachis hypogaea)

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Biochemistry department, Faculty of Science, Alexandria University, Egypt.

Abstract

Background: Lipoxygenases (LOX) are found widely in plants, fungi and animals. These enzymes catalyze the hydroperoxidation of polyunsaturated fatty acids containing cis, cis-1,4-pentadiene moieties. Furthermore, plants contain multiple isoforms of the LOX enzyme which differs in their biochemical properties. Objectives: The present study was carried out to isolate, purify and characterize LOX from peanut seeds. Methods: The concentrated dialyzed cell free extract was fractionated using ammonium sulfate followed by ion exchange chromatography using DEAE-cellulose. SDS-PAGE was performed for the molecular weight determination. Results: Purification of peanut LOX indicates that peanut LOX has three isoenzymes with molecular masses: 113, 113 and 95 KD. The isoenzymes exhibited optimum pH of LOX- 1 and 2 at pH 6 while the optimum pH of LOX -3 was at pH 8. While, the three isoenzymes have the same optimum temperature; 20ᴼC. The Vmax and the Km values of the three isoenzymes were estimated. Our data showed that the LOX activity was irreversibly inhibited by a-chymotrypsin to about 66% as compared to the control. While, atropine had no effect on LOX activity. The heating of peanut at 80ᴼC for 2 and 10 min and at 90ᴼC for 2 min inhibited the LOX activity by about 71.4 %, 84 % and 90.8 %, respectively.  While, the heating of peanut at 80ᴼC for 10 min extend the shelf- life of peanut.                                                                                                                                        2018 Publisher All rights reserved.

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