Fatty acyl ACP

Modulation of the quantity and/or quality of poly(3HAMCL) synthesized in peroxisomes was also achieved by modifying the endogenous fatty acid biosynthetic pathway [58]. For example, expression of the peroxisomal PHA synthase in an A. thaliana mutant deficient in the synthesis of triunsaturated fatty acids [59] resulted in the synthesis of a PHA having an almost complete absence of triunsaturated 3-hydroxyacid monomers [58]. In a different strategy, expression of a fatty acyl-ACP thio esterase in the plastid was combined with the expression of a peroxisomal PHA synthase [58]. Fatty acyl-ACP thioesterases are... 

Production of the four-carbon, saturated fatty acyl-ACP completes one pass through the fatty acid synthase... 

In higher plants, animals, protozoa, and fungi, saturated fatty acids are acted upon by desaturases to introduce double bonds, usually of the cis (Z) configuration. The substrates may be fatty acyl-ACP, fatty acyl-CoA molecules, membrane phospholipids,97 or glycolipids.98 The A9 desaturase, isolated from liver or from yeast, converts stearoyl-CoA to oleoyl-CoA (Eq. 21-3).99-102 This membrane-associated enzyme system... 

As the name anaerobic implies, the double bond of the fatty acid is inserted in the absence of oxygen. Biosynthesis of monounsaturated fatty acids follows the pathway described previously for saturated fatty acids until the intermediate /3-hydroxydecanoyl-ACP is reached (fig. 18.15). At this point, a new enzyme, /3-hydroxydecanoyl-ACP dehydrase, becomes involved. This dehydrase can form the a-j8 trans double bond, and saturated fatty acid synthesis can occur as previously discussed. In addition, this dehydrase is capable of isomerization of the double bond to a cis /3-y double bond as shown in figure 18.15. The /3-y unsaturated fatty acyl-ACP is subsequently elongated by the normal enzymes of fatty acid synthesis to yield pal-mitoleoyl-ACP (16 1A9). The conversion of this compound to the major unsaturated fatty acid of E. coli, cA-vacccnic acid (18 1A11), requires a condensing enzyme that we have not previously discussed, /3-ketoacyl-ACP synthase II, which shows a preference for palmitoleoyl-ACP as a substrate. The subsequent conversion to vaccenyl-ACP is cata-... 

Alkanes are a desirable fuel compound as they have fuel properties nearly identical to that of gasoline. Production of a range of alkanes including nonane and decane has been shown inf. coli [102]. Fatty acyl-ACPs (AGP = acyl carrier protein) were produced through the fatty acid biosynthetic pathway. They were then reduced to aldehydes and decarbonylated to alkanes by an exogenous enzyme, CERl from A. thaliana. 

EN] BRASSICA PLANT COMPRISING MUTANT FATTY ACYL-ACP THIOESTERASE ALLELES. .. 

Plant desaturase systems appear to be soluble, may contain ferredoxin in place of cytochrome 65, and act upon fatty acyl-ACP or upon acyl groups already incorporated into membrane lipids (e.g. [l-oleoyl]-dia-cylgalactosylglycerol desaturated to [l-linoleoyl]-dia-cylgalactosyl ycerol and then to [l-linolenoyl]-diacyl-galactosyl ycerol by spinach chloroplast desaturase). 

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