Lipoxygenase enzyme extraction

The following spectrophotometric methods are conceptually related to the POV however, they are intended for other purposes. HPLC-UVD at 234 nm was applied to detect lipid hydroperoxides, obtained in a set of experiments for assessing the effectiveness of lipoxygenase enzymes extracted from various microorganisms. The absorbance. A, measured at three different wavelengths is linearly correlated to the concentrations in xM units of lipid hydroperoxides, Clh, 7-oxocholesterol, Cqc and dienals, Cde according to the set of simultaneous equations 60. This method was used to track the Cu(II)-induced oxidation of LDL" °. 

Fig. 15.35. Wheat flour quality improvement by the nonspecific lipoxygenase enzyme of soybean (according to Kieffer and Grosch, 1979). Additions 1 control (no addition, bread volume 31 ml), 2 extract of defatted soya meal in which lipoxygenase was thermally inactivated (31 ml), 3 extract of a defatted soya meal with 290 units of lipoxygenase (35 ml), 4 purified type-II enzyme with 285 activity units (37 ml).

The acid-soluble SH-groups in platelets are mainly those of glutathione (GSH). GSH is a cofactor for enzymes such as peroxidase. If feverfew is able to interfere with this cofactor, enzyme function may be impaired. One pathway that may be affected in this way is the metabolism of arachidonic acid (Figure 6.1). In the presence of feverfew extract an increase was found in lipoxygenase product formation and impaired conversion of HPETE to HETE, for which GSH is a cofactor [52]. Inhibition of the liberation of [ " C]arachidonic acid from phospholipids was also found [53], which implies impairment of phospholipase A2 activity and for which SH-groups are thought to be important. 

Albumins and globulins 12-20 Extractable by water of dilute salt solutions (e.g., 0.1-0.5 M NaCl) Contains enzymes (amylases, proteinases, lipoxygenases) Rich in Lys, Asp, Ala, Cys, Leu, and Arg low in Met content... 

The fruits of pomegranate (Punica granatum, L. Punicaceae) are popular in the East and far East countries. The dried pericarp has been utilized in folk medicine for colic, colitis, diarrhea, dysentery, leucorrhea, menorrhagia, oxyuriasis, paralysis and rectocele. The flavonoid extract from cold pressed seed oil showed 31-44% inhibition of sheep COX-1 enzyme and 69-81% inhibition of soybean lipoxygenase [181]. 

Enzymes of Aldehyde Production. Lipoxygenases are discussed elsewhere in this volume. The aldehyde-lyase has only recently been obtained even in crude extracts 145), However, use of 13- and 9-hydroper-oxyoctadecanoic acids to form Cg and C9 aldehydes and corresponding w-oxoacids is evidence that the pathway is correct (145). As with alliinase and myrosinase these reactions occur only when leaves or fruit are cut or crushed (138,143,144,145). If they are heated before blending or blended under N2 (138), little carbonyl compound is formed (142). H2O2 inhibits (138) this reaction as expected for lipoxygenase (153). lrarw-2-Hexenal is formed nonenzymatically from m-S-hexenal (138). 

The cellular locations of leukotriene biosynthesis are determined by the distribution and location of the enzymes needed for their production. 5-Lipoxygenase is found in only a limited number of specific cell types, predominantly of myeloid extraction. Because of this restricted expression, production of LTA4 is largely limited to those cells (e.g., basophils, eosinophils, neutrophils, macrophages, mast cells, and monocytes) (66). These cells produce LTA4, further process it to either LTB4 or LTC4, or secrete it. 

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