Lipoxygenase enzymes

Mechanisms of lipid peroxidation that have been implicated in atherosclerosis may be pertinent to RA. Cellular lipoxygenase enzymes may promote LDL modification by inserting hydroperoxide groups into unsaturated fetty-acid side chains of the LDL complex (Yla-Herttuala etal., 1990). 15-Lipoxygenase has been implicated as an initiator of LDL oxidation (Cathcart etal., 1991) whilst 5-lipoxygenase does not appear to be involved (Jessup et al., 1991). Products of activated lipoxygenase enzymes within inflammatory synovial fluid surest that this pathway could be activated in RA (Costello etal., 1992). 

TLi used was between 0 and 7.33 mM (equivalent to 22 mM LA). TL initially dissolved in the organic phase, was hydrolyzed in the presence of the lipase at the liquid-liquid interface. Liberated LA transferred to the aqueous phase in which it reacted with lipoxygenase. Enzyme preparations and concentration were the same as those already chosen for determination of kinetic constants. 

The reason for the non-response of the Hagberg Falling Number to fungal a-amylase is that it is inactivated at 75°C rather than the 87°C of cereal a-amylase. It turns out that fungal a-amylase preparations improve loaf volumes considerably. Most of this effect is produced by a lipoxygenase enzyme that is also present. 

CysLTs) are proinflammatory molecules synthesized primarily by basophils, neutrophils, and mast cells and are potent mediators of airway inflammation and bronchoconstriction (77,78). There are two classifications of drugs in this category that can regulate the effects of CysLTs inhibitors of the 5-lipoxygenase enzyme, such as zileuton, and CysLT receptor antagonists, such as montelukast and zafirlukast. 

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" °. 

Leukotriene One of the 20-carbon fatty acid compounds (eicosanoids) formed from arachidonic acid by the lipoxygenase enzyme. Leukotrienes are important in mediating certain allergic and inflammatory responses, especially in respiratory tissues. 

Oomah, B.D., Kenaschuk, E.O., and Mazza, G. 1997b. Lipoxygenase enzyme in flaxseed. J. Agric. Food Chem. 45, 2426—2430. 

This group of compounds is formed from the lipid fraction of the juice, through the sequential action of several enzymes. In Fig. 4.2. the mechanism described by Crouzet (1986) for the formation of cis-3- and tran5 -2-hexanal and their corresponding alcohol is shown. Linolenic acid is a common constituent of grape juice. Through the action of a lipoxygenase enzyme, linolenic acid is transformed... 

Figure 13. Effect of extrusion temperature on protein dispersibility index (PDI) and lipoxygenase enzymes activity (LOX).

Inhibitor of the S-lipoxygenase enzyme necessary for the biosynthesis of leukotrienes including LTD,. 

Inhibition of PG biosynthesis by open chain diarylheptanoids was first reported by Itokawa and his coworkers (26, 31). Their results were implemented by studies on additional compounds first by Flynn (88) and later by Kinchi et al. (85). The latter group extended the assay of inhibitor activity also to the 5-lipoxygenase enzyme system. Their results are summarized in Table 2. Among macrocyclic diarylheptanoids only for garuganins (88-95), isolated from Garuga pinnata was some antiinflammatory activity claimed, but no specific data were disclosed (57, 58). 

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