Cinnamate decarboxylase

Precursors. Both hydroxycinnamic acids and 4-vinylphenols can lead to the formation of hydroxyphenyl-pyranoanthocyanins. The main hydroxycinnamic acids present in wines are p-coumaric, caffeic, ferulic and sinapic acids. 4-Vinylphenol and 4-vinylguaiacol are volatile phenols associated with off flavors in wine (Eti6vant 1981) and arise from the decarboxylation of p-coumaric and ferulic acid, respectively, via the yeast cinnamate decarboxylase (CD) (Chatonnet et al. 1993). 

The precursors of VPs are hydroxycinnamic acids which are enzymatically decar-boxylated by a cinnamate decarboxylase, leading to vinylphenol derivatives, and... 

During fermentation, S. cerevisiae may produce vinylphenol derivatives due to the presence of cinnamate decarboxylase enzymes (Chatonnet et al. 1992, 1993) which are inactive in red juices due to the polyphenol components of red wine (Chatonnet et al. 1997). Several grape juice contamination yeast species also have the ability to form vinylphenols (Dias et al. 2003a) but their contribution to the vinylphenol content of wines may only be relevant when are not inhibited by S. cerevisisiae (Barata et al. 2006). 

The cinnamate decarboxylase (CD) of Saccharomyces cerevisiae is highly specific. These yeasts are incapable of converting benzoic acids into volatile phenols. Only certain acids in the cinnamic series (phenyl-propenoic acids) may be decarboxylated by this microorganism. Among the cinnamic acids in grapes, only ferulic and p-coumaric acids are affected by the CD activity. Caffeic (4,5-dihydroxycinnamic) and sinapic (4-hydroxy-3,5-dimethoxycinnamic) acids are not decarboxylated by S. cerevisiae. Cinnamic acid and... 

The use of certain pectolytic enzyme preparations to facilitate the extraction or clarification of white must may lead to an increase in the vinyl-phenol content of white wines and a deterioration of their aromatic qualities (Chatonnet et al 1992a Dugelay etal., 1993 Barbe, 1995). Indeed, certain industrial pectinases, made from Aspergillus niger cultures, have a cinnamyl esterase (CE) activity. This enzyme catalyzes the hydrolysis of tartrate esters of hydroxycinnamic acids in must during the pre-fermentation phase (Figure 8.7). Feruhc and j9-coumaric acids are then converted into vinyl-phenols during alcohohc fermentation due to the cinnamate decarboxylase activity of Saccharomyces cerevisiae. 

A stndy of the mechanisms by which Brettanomyces biosynthesizes ethyl-phenols demonstrated the seqnential action of two enzymes (Figure 8.11). The first is a cinnamate decarboxylase that transforms cinnamic acids into vinyl-phenols. This enzyme, nnlike that of Saccha-romyces cerevisiae, is capable of decarboxylating... 

It is believed that these compounds, characteristic of Brettanomyces and Dekkera, result from decarboxylation of hydroxycinnamic acids, yielding vinyl phenol intermediates and subsequent reduction to produce the ethyl analog (Steinke and Paulson, 1964). As seen in Fig. 3-3 initial decarboxylation is mediated by cinnamate decarboxylase, whereas the reduction step utilizes a vinyl phenol reductase. 

Dubourdieu (1992) points out that wine yeasts Saccharomyces cerevisiae also contains the cinnamate decarboxylase and thus are capable of producing the vinyl phenol intermediate. However, flavonoid phenols (tannins) inhibit its activity hence, the formation of volatile phenols in red and rose wines is significantly less than that seen in white wine fermentations. Activity of cinnamate decarboxylase in the case of Brettanomyces and Dekkera, however, is not inhibited by polymeric phenols. 

Biochemically, 4-ethyl guaiacol and 4-ethyl phenol originate from ferufic acid and /vcoumaric acid, respectively. The reaction is a two-step process with an initial decarboxylation of the hydroxycinnamic acids catalyzed by cinnamate decarboxylase and the reduction of the vinyl phenol intermediates by vinyl phenol reductase (Fig. 11.1). Although the specific coenzyme involved remains unknown, one possible metabolic benefit of the second reaction to Brettanomyces could be reoxidation of NADH. Under low oxygen conditions such as those found in wines, the availability of NAD can be limited so that carbohydrate metabolism is inhibited (Section 1.5.1). Reduction of the vinyl phenols to the ethyl phenols would allow the cell to increase the availability of NAD and thus maintain metabolic functions. 

In any case, care should be taken to avoid enzyme preparations containing cinnamate decarboxylase as it may lead to the development of ethyl-phenols with a highly unpleasant musky odor... 

Enzymatic preparations should never contain cinnamate decarboxylase. This enzyme can lead to the formation of ethyl-phenols with a very disagreeable animal odor (Chapter 2). 

Other strains, like VLl, were selected for their low vinyl-phenol production. These compounds possess rather unpleasant pharmaceutical aromas. Above a certain concentration, they dull the aroma of dry white wines (Volume 2, Sections 8.4.2 and 8.4.3). These strains have low cinnamate decarboxylase activity. During alcoholic fermentation, this enzyme catalyzes the partial transformation of p-coumaric and ferulic acid found in juice into vinyl-4-phenol and vinyl-4-gaiacol. Since this enzyme is inhibited by phenolic compounds, only white wines can contain quantities of vinyl-phenols likely to affect their aroma. The use of strains with low cinnamate decarboxylase activity is recommended— particularly for white juices containing high concentrations of hydroxy cinnamic acid. 

Clausen, M., Lamb, C. J., Megnet, R., Doemer, P. W. (1994) PADl encodes phenylacryUc acid decarboxylase which confers resistance to cinnamic acid in Saccharomyces cerevisiae. Gene, 142, 107-112. 

Hagel,J.M. and P.J.Facchini Elevated tyrosine decarboxylase and tyramine hydroxycinnamoyltransferase levels increase wound-induced tyramine-derived hydroxy-cinnamic acid amide accumulation in transgenic tobacco leaves Planta 221 (2005) 904-914. 

Figure 3. Proposed pathways to AA precursors. A) 3,4-dihydroxybenzaldehyde (3,4-DHBA) biosynthesis depicting the two possible routes from/ -coumaric acid to form 3,4-DHBA the oxidative ferulate and the non-oxidative benzoate pathways B) Tyramine biosynthesis. Arrows without labeling reflect chemical reactions that have not been enzymatically characterized. Enzymes that have been cloned, characterized and identified are labeled in black bold. Enzyme abbreviations PAL, phenylalanine ammonia -lyase C4H, cinnamate 4-hydroxylase C3H, coumarate 3-hydroxylase HBS, 4-hydroxybenzaldehyde synthase TYDC, tyrosine decarboxylase.

Aspartic acid, alanine, phenylalanine, and lysine were manufactured by enzymatic route. Immobilized E. coli cells expressing aspartate or the immobilized enzyme has been used in the commercial production of aspartic acid from ammonia and fumaric acid. Chibata and coworkers also produced alanine by microbial Pseudomonas dacunhae) L-aspartate P-decarboxylase with aspartate as the starting material. Phenyl alanine was manufactured from fw s-cinnamic acid and ammonia by the enzymatic route by phenyl alanine ammonia lyase as catalyst or from phenyl pyruvate and aspartic acid using transaminase. 

The biosynthesis of other volatile phenyl-propanoid-related compoimds such as phenyla-cetaldehyde and 2-phenylethanol, does not occur via trans-cinnamic acid and competes with PAL for Phe utilization [90, 96, 97]. Phenylacetaldehyde biosynthesis from Phe requires the removal of both the carboxyl and amino groups. A classical sequential two-step removal is believed to occur in tomato where Phe was shown to be first converted to phe-nylethylamine by aromatic amino acid decarboxylase (AADC) and further required the action of a hypothesized amine oxidase, dehydrogenase, or transaminase for phenylacetaldehyde formation [97]. On the other hand, in petunia, one bifunctional enzyme, phenylacetaldehyde synthase (PAAS) catalyzes the unprecedented efficient coupling of Phe decarboxylation to oxidation resulting in... 

A large number of inhibitors of DOPA decarboxylase have been described a few of the most imtent compounds are listed in Table 7. Inhibitors include DOPA analogues such as a-methylDOPA. cinnamic acid derivatives and hydrazino compounds. Although many of these compounds are effective inhibitors of the enzyme in vivo, there is such a Mgh DOPA-decarboxylase activity in most tissues that it has proved very difficult to produce any significant inhibition of catechohunine bio-... 

The overexpression of the PADl (phenylaerylie acid decarboxylase gene) from S. cerevisiae, resulted in an ethanol productivity improvement in the presence of ferulic acid and cinnamic acid. The PADl overexpressing strain also showed 22-25%, 24-29% and 40-45%, faster glucose consumption... 

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