Iron -lipoxygenase

A similar W-band study was performed on a new variant of lipoxygenase in which the iron is replaced by manganese (MnLO). Compared with X-band, the signal was considerably simplified at W-band and allowed estimates of the zero-field splitting parameter (D = 0.07-0.1 cm ) and E/D (0.13-0.23), which indicated that the coordination environment of MnLO is similar to that in iron lipoxygenase. ... 

Pistorius, E.K. and Axelrod, B. (1976). Evidence for partidpation of iron in lipoxygenase reaction from optical and esr studies. J. Biol. Chem. 251, 7144-7148. 

Lipoxygenase (EC 1.13.11.12, nonheme iron dioxygenase), the substrate (polyunsaturated fatty acid) is poorly water soluble and the product (hydroperoxy-fatty acid) is hydrophilic. The reaction occurs in the aqueous phase [85,86]. 

Flavonoids exhibit protective action against LDL oxidation. It has been shown [145] that the pretreatment of macrophages and endothelial cells with tea flavonoids such as theaflavin digallate diminished cell-mediated LDL oxidation probably due to the interaction with superoxide and the chelation of iron ions. Quercetin and epicatechin inhibited LDL oxidation catalyzed by mammalian 15-lipoxygenase, and are much more effective antioxidants than ascorbic acid and a-tocopherol [146], Luteolin, rutin, quercetin, and catechin suppressed copper-stimulated LDL oxidation and protected endogenous urate from oxidative degradation [147]. Quercetin was also able to suppress peroxynitrite-induced oxidative modification of LDL [148],... 

Both lipases and lipoxygenases are present in the bran and the germ. Phytases are nutritionally important as they liberate the phosphorus, of which approximately 70% is in the kernel bound to phytin. Phytin blocks the intestinal absorption of both iron and calcium. Phytase is also present in yeast, which is why leavened bread is nutritionally superior to unleavened bread. There have been concerns about the incidence of rickets among those of South Asian origin who eat chapattis, live in the UK, and have a tendency to keep their skin covered up from the sun. 

Lipoxygenase [EC 1.13.11.12] catalyzes the reaction of linoleate with dioxygen to produce (9Z,11 )-(135 )-13-hydroperoxyoctadeca-9,ll-dienoate. This iron-depen-dent enzyme can also oxidize other methylene-interrupted polyunsaturated fatty acids. See also specific enzyme... 

This iron-dependent enzyme [EC 1.13.11.34], better known as arachidonate 5-lipoxygenase and occasionally referred to as leukotriene A4 synthase, catalyzes the reaction of arachidonate with dioxygen to produce (6 , 8Z,1 lZ,14Z)-(5S)-5-hydroperoxyicosa-6,8,ll, 14-tetraenoate, which rapidly converts to leukotriene A4. 

In 1990, Triantaphylidds and coworkers reported on the preparative enzymatic synthesis of hnoleic acid (135) hydroperoxide 24a using soybean lipoxygenase-1. In this dioxygenation asymmetry is induced by the catalyst, the enzyme. The reaction was later used by Dussault and also by Baba and coworkers as key step in the preparation of more complex peroxides. The enzyme is a non-heme iron dioxygenase which catalyzes the incorporation of dioxygen into polyunsaturated fatty acids to yield E,Z conjugated diene hydroperoxides 24a-d. With this enzymatic method, the hydroperoxide 24a could... 

Lipoxygenase (LOX) is a non-haem, iron-containing dioxygenase that catalyses the regioselective and enantioselective dioxygenation of unsaturated fatty acids containing at least one (Z,Z)-l,4-pentadienoic system. For instance, LOX from soy converts linoleic acid to the (S)-13-hydroperoxide [1]. 

Iron-containing superoxide dismutases are present in many species of bacteria (Hassan and Fridovitch, 1978). These nonheme iron proteins have a characteristic set of EPR lines split about g = 4.2 in the ferric state, arising from the middle Kramers doublet of a rhombic high-spin site. Ferrous iron superoxide dismutase forms an S = I complex with NO that resembles the lipoxygenase-NO adduct by EPR criteria (I. Fridovich, T. Kirby, and J. C. Salerno, (1978) unpublished observations). 

LDL becomes oxidized in vivo. There is evidence that LDL is protected against oxidation in plasma by water-soluble antioxidative substances, such as ascorbic acid, uric acid, or bilirubin. Thus, it is likely that the majority of oxidative modification of LDL occurs in the artery wall, where LDL is largely isolated from the plasmatic antioxidants. Recent evidence suggests that metal ions (copper or iron) and the enzymes myeloperoxidase and lipoxygenase play major parts in the modification of LDL [161]. 

Lipoxygenase (EC 1.13.11.12) is an enzyme that catalyzes the hydroperoxidation of polyunsaturated fatty acids and esters containing a cis-cis-l, 4-pentadiene system (Table 6). In 1947, Theorell et al. obtained the enzyme in a crystalline form from soybeans and reported that the enzyme neither contained nor required a metal cofactor192. Subsequent studies from three groups of investigators have demonstrated that the enzyme purified from soybeans in an iron-containing dioxygenase74-76 ... 

These results indicate that the Fusarium lipoxygenase differs from the soybean lipoxygenase in various respects soybean lipoxygenase is a nonheme iron-containing dioxygenase and has a molecular weight of 102,000, optimum pH of 6.5 to 7,0 and isoelectric point of pH 5.4. The soybean enzyme is not inhibited by cyanide and catalyzes the peroxidation of linoleic acid and linolenic acid at equal rates74-76,193. ... 

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