Purification and some properties of wheat germ lipoxygenase

Abstract

Lipoxygenase from the germ of bread wheat was purified to near homogeneity by a classical scheme. After extraction at pH 4.5 from defatted germ, lipoxygenase activity was precipitated by 40 % saturation (NH&S04 from a 25 % saturation supernatant.After dissolution in a phosphate buffer at pH 7 and extensive dialysis against this buffer, the extract was submitted to gel filtration on Ultrogel AcA 34. The final step of DEAE Sephadex A50 chromatography gave three peaks ( b , La and L3) with lipoxygenase activity. The total yield of the purification procedure was close to 307; and the degree of purification varied from 200 to 300 depending on the fraction considered. The three isoenzymes were also detected by disc electrophoresis using a specific staining method and were isolated by isoelectric focusing in a liquid medium. The molecular weight for each isoenzyme was determined to be 90 000-95 000 by gel filtration and 110 000 by electrophoresis in a gradient of acrylamide concentration. The stability, pH optimum and calcium effect have been studied. LZ and L3 were less stable than L1. Optimum pH ranged between 6-6.5 and neither isoenzyme activity was affected by calcium ions. L1 was twice as active towards j3-carotene as LZ and L3 for the same level of oxygen uptake, but in comparison to lipoxygenase from horsebean the co-oxidising power of wheat lipoxygenase was very poor.

Impact of high intensity pulsed electric field on antioxidant properties and quality parameters of a fruit juice–soymilk beverage in chilled storage

“…The behaviour exerted by LOX in the FJ-SM beverage throughout the storage can be explained by two possible hypothesis: i) inactivation of enzymes could be reversible and the enzymes can recover their activity under certain conditions (Bahçeci, Serpen, Gö kmen, & Acar, 2005) or ii) the presence of different isoenzymes in the FJ-SM beverage, which could be more resistant to HIPEF process; therefore, they could increase their activity over time. According to different authors, there are apparently 3 to 4 isoenzymes of LOX in different vegetable products which differ in their thermal stability (Engeseth, Klein, & Warner, 1987;Hildebrand, 1989;Nicolas, Austran, & Drapon, 1982;Shiba, Negishi, Okada, & Nagao, 1991). Ling and Lund (1978) based on the presence of two isoenzymes groups with distinct thermal stabilities, observed that the heat labile fraction can inactivate rapidly whereas that heat-resistant cannot be inactivated completely.…”

Antioxidant composition and activity of barley (Hordeum vulgare) and malt extracts and of isolated phenolic compounds

“…, 19 the cooxidation of b-carotene in a linoleate model system 11 and the inhibition of lipoxygenase activity. 20,21 Standards and compounds isolated from barley were used at 1 mg ml À1 and diluted between 20 and 200 times in MeOH. Each malt and barley extract was ®rst diluted in MeOH and named antioxidant solution.…”

PURIFICATION AND CHARACTERIZATION OF LIPOXYGENASE ISOZYMES FROM CANOLA (Brassica napus cv, WESTAR) SEED

“…With conventional chromatography, three isozymes were reported for peanut lipoxygenase (Sanders er al. 1975) and for wheat germ lipoxygenase (Nicolas et al 1982). However, the number of isozymes varied according to the source and these differences could be attributed also to the chromatographic conditions and techniques used (Haydar et al 1975 chromatography, the degree of purification for pea lipoxygenase was 73-fold (Arens et al 1973) and 33-fold (Eriksson and Svensson 1970), for pea seeds lipoxygenase was 23.4-fold (Haydar and Hadziyev 1973) and for wheat lipoxygenase was 102-fold (Wallace and Wheeler 1975).…”