Fatty hydroperoxide lyase

In plant tissues, various enzymes convert the hydroperoxides produced by LOX to other products, some of which are important as flavor compounds. These enzymes include hydroperoxide lyase, which catalyzes the formation of aldehydes and oxo acids hydroperoxide-dependent peroxygenase and epoxygenase, which catalyze the formation of epoxy and hydroxy fatty acids, and hydroperoxide isomerase, which catalyzes the formation of epoxyhydroxy fatty acids and trihydroxy fatty acids. LOX produces flavor volatiles similar to those produced during autoxidation, although the relative proportions of the products may vary widely, depending on the specificity of the enzyme and the reaction conditions. 

MATSUI, K., SHIBUTANI, M., HASE, T., KAJIWARA, T., Bell pepper fruit fatty acid hydroperoxide lyase is a cytochrome P450 (CYP75B) in many plant tissues, FEBS Lett., 1996, 394,21-24. 

MATSUI, K., WILKINSON, J., HIATT, B., KNAUF, V., KAJIWARA, T., Molecular cloning and expression of Arabidopsis fatty acid hydroperoxide lyase, Plant Cell Physiol., 1999,40,477-481. 

The volatiles produced by the LOX pathway and autoxidation are typically volatile aldehydes and alcohols responsible for fresh and green sensorial notes. In the LOX pathway these volatile compounds are produced in response to stress, during ripening or after damage of the plant tissue. The pathway is illustrated in Scheme 7.2. Precursors of the LOX (EC 1.13.11.12) catalysed reactions are Cis-polyunsaturated fatty acids with a (Z,Z)-l,4-pentadiene moiety such as linoleic and a-linolenic acids that are typically oxidised into 9-, 10- or 13-hydro-peroxides depending on the specificity of the LOX catalyst. These compounds are then cleaved by hydroperoxide lyase (HPL) into mainly C, C9 and Cio aldehydes, which can then be reduced into the corresponding alcohols by alcohol dehydrogenase (ADH EC 1.1.1.1) (Scheme 7.2) [21, 22]. The production of volatile compounds by the LOX pathway depends, however, on the plants as they have different sets of enzymes, pH in the cells, fatty acid composition of cell walls, etc. 

Oxidative cleavage of unsaturated fatty acids by lipoxygenase and hydroperoxide lyase... 

In nature, the green notes are produced after the destruction of the plants tissue (leaves, fruits or vegetables). Destruction of the cell wall leads to a cascade of enzyme-catalysed reactions polyunsaturated fatty acids with the diene system described before are converted into hydroperoxides by LOX catalysis. The hydroperoxide lyase cleaves the hydroperoxides in the whole cascade, oxireduc-tases are involved too. The biotechnological large-scale production of natural green notes follows the natural pathway. 

FIGURE 7.6 Short-chain aldehydes and alcohols produced from the degradation of fatty acids in grapes via the lipoxygenase (LOX)/hydroperoxide lyase (HPL) pathway during the prefermentative stages of vinification (adapted from Camara, 2004). 

FROELICH, J.E., ITOH, A., HOWE, G.A., Tomato allene oxide synthase and fatty acid hydroperoxide lyase, two cytochrome P450s involved in oxylipin metabolism, are targeted to different membranes of chloroplast envelope., Plant Physiol., 2001,125,306-317. 

The formation of Cg aldehyde and alcohols in plant tissues is related to cell destruction. Disruption of intact cells during crushing and milling results in the release of lipid-degrading en2ymes, lipoxygenases and fatty acid hydroperoxide lyase, which cleave the fatty acid moiety to Cg... 

Tijet, N. et al., Purification, molecular cloning and expression of the gene encoding fatty acid 13-hydroperoxide lyase from guava fruit (Psidium guajava), Lipid, 35, 709, 2000. 

Fatty Acid Hydroperoxide Lyase in Plant Tissues... 

Fatty acid hydroperoxide lyase is one of the enzymes responsible for volatile Cft- and C9-aldehyde formation from linoleic and linolenic acid. This enzyme cleaves 9- and/or 13-hydroperoxides derived from linoleic and linolenic acid. The enzyme is distributed in a wide range of plant species in membrane bound forms both chloroplastic and non-chloroplastic. Three types of hydroperoxide lyases have been reported 9-hydroperoxide-specific, 13-hydroperoxide-specific and nonspecific. Other properties of the hydroperoxide lyase including substrate specificity and reaction mechanism are discussed in this review. 

The unsaturated Cg aldehydes and alcohols probably arise in wheat from cleavage of the 9—10 double bond of unsaturated C g fatty acids, linoleic and linolenic acids (Figure 2). Galliard and coworkers (12,13) have partially purified enzyme systems capable of catalyzing these transformations. Lipoxygenase initially converts linoleic and linolenic acids to 9-hydroperoxides which are subsequently cleaved by hydroperoxide lyase to volatile Cg unsaturated aldehydes and 9-oxo-nonanoic acid. The 3-enals are the primary volatile cleavage products from the fatty acids and these are transformed by an isomerase to the more stable 2—enals (14). The 3—enals are rather unstable but Hatanaka et al. (15) have confirmed their presence in plant tissue with authentic samples. The Cg... 

Fig. 8. Metabolism of 18 3 fatty acid to oxylipins. I. Lipoxygenase 2, alleneoxide synthase 3, allene oxide cyclase 4, 12-oxo-phytodienoic acid reductase, -oxidation 5, hydroperoxide lyase.

J. F. Vliegenthart (2001). Fatty acid hydroperoxide lyase A plant cytochrome p450 enzyme involved in wound healing and pest resistance. ChemBioChem 2, 494-504. 

Howe, G.A., G.I. Lee, A. Itoh, L. Li, and A.E. DeRocher (2000). Cytochrome P450-depend-ent metabolism of oxylipids in tomato. Cloning and expression of allene oxide synthase and fatty acid hydroperoxide lyase. Plant Physiol. 123, 711-724. 

Another example is the production of green note compounds using lipoxygenase pathway enzymes. Lipoxygenase and hydroperoxide lyase are the determinant enzymes for the conversion of fatty acids into natural food flavor components. However, these compounds present in natural sources at very low levels and because of their instable nature it has been difficult to purify these compounds. As a result, considerable efforts have been made to clone these two enzymes for commercial uses in the production of natural flavor components. Many plant lipoxygenase from different plants have been cloned and expressed in E. coli or yeast [5],... 

Kuroda H, Oshima T, Kaneda H, Takashio M (2005) Identification and functional analyses of two cD-NAs that encode fatty acid 9-/13-hydroperoxide lyase (CYP74C) in rice. Biol Biotechnol Biochem 69 1545-1554... 

Hydroperoxide lyases cleave the peroxidic fatty acids to form aldehydes ... 

Shibata, Y., Matsui, K., Kajiwara,T., Hatanaka, A. Purification and properties of fatty acid hydroperoxide lyase from green bell pepper finits. Plant Cell Physiol 36(1) (1995), 147-156... 

Motsui, K., Toyota, H.,Kajiwara, T. and Hatonaka, A. (1991) Fatty acid hydroperoxide cleaving enzyme, hydroperoxide lyase, from tea leaves, Phytochem., 30, 2109-2113. 

PURIFICATION AND MOLECULAR CLONING OF BELL PEPPER FRUIT FATTY ACID HYDROPEROXIDE LYASE... 

S)-hydroperoxy-(9Z,11E,15Z)-octadecatrienoic acid Fatty acid hydroperoxide lyase... 

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