Biosynthesis Butyric acid

Butyric acid is one of the simplest fatty acids. Fatty acids, which are the building units of fats and oils, are natural compounds of carbon chains with a carboxyl group (-COOH) at one end. Most natural fatty acids have an unbranched carbon chain and contain an even number of carbon atoms because during biosynthesis they are built in two carbon units from acetyl coenzyme A (CoA). Butyric acid is an unsaturated fatty acid, which means all carbon-carbon bonds are single bonds. Common names for fatty acids stem from their natural sources. In addition to butyric acid, some other common saturated fatty acids include lauric acid, palmitic acid, and stearic acid. Lauric acid was first discovered in Lauraceae (Laurus nobilis) seeds, palmitic oil was prepared from palm oil, and stearic acid was discovered in animal fat and gets its name from the Greek word stear for tallow. 

Induction of Ganglioside Biosynthesis in Cultured Cells by Butyric Acid... 

Scheme 1.6.2. Biosynthesis of /i-alanine 3 and (R)-/ -aminoiso-butyric acid [(/ )- 0], respectively by degradation of pyrimidines.

In a series of labeling experiments, the biogenesis of esters and alcohols by fruit tissue slices was investigated (7y .) While (U—1 4c) -acetate and (U-1 c) -butyrate were incorporated into the corresponding esters by postclimacteric banana tissue, (U-14c)-octanoate was transformed in climacteric and postclimacteric banana tissues into caproic and butyric acid by B-oxidation and into heptanoic acid by ot-oxidation (9). In addition, 1-octa-nol, Z-4-hepten-2-ol, pentanol-2 and the corresponding esters were labeled. The biosynthesis of alcohols and esters is an analogous reaction to the formation of wax esters as outlined by Kolattukudy ( O). Octanoyl-CoA is reduced by an acyl-CoA reductase (NADH dependent) to octanal which is further transformed into 1-octanol by an... 

The pentapeptide chains of peptidoglycans have a sequence of amino-acids terminated with D-Ala-D-Ala at positions 4 and 5. Possible conformations of D-Ala-D-Ala and its analogues L-Ala-D-Ala, D-Ala-L-Ala, D-butyryl-L-Ala, D-Ala-D-butyric acid, D-Val-D-Ala, and D-Ala-D-Val have been analysed by theoretical methods.From theoretical studies it is predicted that L-Ala or D-Val at the 4 or 5 position of the pentapeptide group of the peptidoglycan will reduce the cross-linking in peptidoglycan biosynthesis, whereas the effect of D-butyric acid will be marked at the 4 position and moderate at the 5 position. This is in agreement with experimental results. 

The microbial biosynthesis of P(3HB-4HB) copolymers was achieved using different nutritional strategies. Most of them are based on the carbon sources used to feed the cultures (butyric acid and different sugars, or a single carbon source structurally related to butyric acid such as 4-hydroxybutyric acid, y-butyrolactone or 1,4 butanediol Saito and Doi 1994 Kunioka et al. 1989). 

In Europe and the United States, a mixture of taUow and coconut oil is generally used. Palm oil and pahn kernel oil are used more frequently in the producing areas such as Africa and southeast Asia. Each fat molecule is made up of complex mixtures of natural fatty adds of different chain lengths from C4 (butyric acid) to C22 (erucic acid) (Table 25.1). The chains of fatty adds, which are derived from biosynthesis, are built from two carbon units, and cis double bonds are inserted by desaturase enzymes at specific positions resulting in even-chain-length fatty acids. The most common acids are Cjg and Cjg. 

Five-carbon compounds are formed from (S)-aceto-2-hydroxy-butyric acid, also known as (S)-2-ethyl-2-hydroxy-3-oxobutanoic acid, which is the intermediate of isoleucine biosynthesis from threonine. This acid is formed in the reaction of 2-oxobutanoic acid with acetaldehyde and its decarboxylation provides R)-3-hydroxypentane-2-one, which is oxidised to pentane-2,3-dione and reduced to (21 ,31 )-pentane-2,3-diol (Figure 8.13). 

Carbohydrates are also precursors of carboxylic adds. Bacteria of the genera Clostridium, Butyribacterium and Butyrmbrio ferment sugars primarily to acetic and butyric acids. Bacteria of the genus Propionibacterium (P. freudenreichii subsp. shermanii) ferment lactose to lactic acid, which is reduced to propionic acid, an important add of the most famous Swiss cheese, Emmental (Figure 8.39). The first step of this biosynthesis is the reaction of... 

The first reported study on the biosynthesis of nocardicin A was by Hosoda etal, who administered a variety of C-labelled compounds to shaken fermentations of Nocardia miformis subsp. tsuyamonensis 206). Examination of the resulting nocardicin A showed that L-[U- C]-tyrosine, [G- CJ-shikimic acid, and L-[U- C]-serine were all incorporated into the antibiotic. [U- C]-Glycine and L-[U- C]-homoserine were also incorporated but to a lesser degree, whereas the labels from L-[l- C]-tyrosine, L-[U- C]-phenylalanine, L-[U- C]-alanine and DL-[U- C]-a-amino-butyric acid were not incorporated to any significant extent. 

In the first example, the sodium enolate of (S)-4-benzyl-3-[ 1 - " C]butyryl-1,3-oxazolidin-2-one (93) was treated with a tenfold excess of methyl iodide to afford a 95 5 mixture of the two a-methylated diastereomers 94 and 95. Preparative HPLC separation of 94 followed by cleavage of the auxiliary provided the free (S)-2-methyl[l- C]butyric acid (96) in overall 58% yield from sodium [l- " C]butyrate. Acid 96 was a key intermediate in the carbon-14 labeling of pravastatin, an antihyperlipoproteinemic drug, as well as for investigation of the biosynthesis and the biological labeling of avermectin Bia, currently marketed as a miticide/ insecticide . 

Liu, S.J. Steinbuchel, A. Exploitation of butyrate kinase and phosphotransbutyrylase from Clostridium acetobutylicum for the in vitro biosynthesis of poly(hydroxyalkanoic acid). Appl. Microbiol. Biotechnol., 53, 545-552 (2000)... 

Exposure of HeLa cells to butyrate had no effect on the activity of GM3-sialidase when GM3 specifically labeled in the sialic acid residue was used as substrate (Fig. 3a). We were unable to detect any "ecto"-sialidase activity in either control or butyrate-treated cells (14) although others have postulated that such an enzyme is important in regulating plasma membrane gangliosides (15,16). In contrast, the activity of the specific sialyl transferase involved in GM3 biosynthesis increased over 20-fold following butyrate treatment (Fig. 3b). The effect was specific as activities of the other glycosphingolipid transferases that could be measured in HeLa cells were not altered in butyrate-treated cells (4,8,17). 

Figure 6.7 Biosynthesis of (2 ,4 ,6 )-5-ethyl-3-methyl-2,4,6-nonatriene, pheromone component of Carpophilus freemani Dobson (Nitidulidae). The pathway is a modification of normal fatty acid biosynthesis, involving initiation with acetate elongation with first propionate (to provide the methyl branch), then butyrate (to provide the ethyl branch) and chain termination with a second butyrate. The final butyrate to add suffers a loss of C02, after adding in a unique head-to-head reaction. Intermediates of the pathway likely occur as activated (e.g. CoA) derivatives (Petroski et al., 1994 Bartelt and Weisleder, 1996).

There are two principal ways for utilization of microorganisms (yeasts, fungi, bacteria) for the production of flavouring substances, i.e. fermentation (de novo biosynthesis) and biotransformation (Tab. 3.7). Fermentation products are usually complex (see 3.2.2.4.). Nevertheless, there are some single flavouring substances that are produced by fermentation, such as acetic, butyric, and propionic acids and others (Tab. 3.8). For biotransformations by microorganisms, suitable substrates are necessary. Some examples are given in Tab. 3.9 and Fig. 3.5. 

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