Phenylalanine cinnamic acid

The conversion of phenylalanine to a C-6—C-1 unit must include a process for the loss of two earbon atoms of the aromatic side chain as well as the introduction of oxygen in the aromatic ring. From previous biochemical studies two possible pathways seemed feasible for degradation to a C-6—C-1 unit (a) phenylalanine->phenylserine->benzalde-hyde- protocatechuic aldehyde, or (6) phenylalanine- cinnamic acid- -caffeic acid->protocatechuic aldehyde. The negligible incorporation of benzaldehyde and phenylserine compared with protocatechuic aldehyde... 

Most of the biogenetic proposals for the elaboration of the A ring involved the use of phenylalanine or its biochemical equivalent, dl-Phenylalanine-3-i4C was fed (58) as a means of determining which of these possibilities was closer to the true situation. The colchicine activity from this experiment was found almost entirely at C-5, an observation which negates the first two schemes illustrated in Section VII, A. DL-Phenylalanine-2-i4C (59, 62, 64) and DL-phenylalanine-l- C (62, 64) were found to label specifically carbon atoms 6 and 7, respectively. Sodium cinnamate-2- and 3- C were also incorporated (62, 64, 65) specifically into carbons 6 and 5, respectively. The firm conclusion can be reached that the phenylalanine-cinnamic acid pathway is used in the elaboration of ring A and carbon atoms C-5, C-6, and C-7. Similar results were found with demecolcine (6, 59). L-Methionine-i CHa (6, 61) and other C-1 donors (see Table VI), as expected, were excellent sources of the (9-methyl groups. 

In virus-inoculated tobacco, benzoic acid is converted by the monooxygenase enzyme, benzoic acid 2-hydroylase, into salicylic acid. NADPH was required. Feeding of phenylalanine, cinnamic acid, or o-coumaric acid (all potential precursors) failed to induce the enzyme (Leon et al., 1993). 

In a series of feeding experiments, it was found that phenylalanine, cinnamic acid, wera-coumaric acid, and dihydro-m-coumaric acid were good precursors for orchinol (20) and hircinol (21) in Orchis militaris, but o- and p-coumaric acids were not. The production of both meta-substituted compounds in this orchid was confirmed (Dewick, 1984). Incor-... 

Utilization of the 3-carbon side chain of the phenylalanine-cinnamic acid intermediates for the construction of the pyridine ring in the A4 alkaloid, as indicated in Schemes 45 and 46, is easily ascertained in principle by an... 

The precursors of flavonoid biosynthesis include shikimic acid, phenylalanine, cinnamic acid, and p-coumaric acid. Shikimic acid acts as an intermediate in the biosynthesis of aromatic acid. The basic pathways to the core isoflavonoid skeletons have been established both enzymatically and genetically [16]. The synthesis of isoflavones can be broadly divided into three main synthetic pathways the formylation of deoxybenzoins, the oxidative rearrangement of chalcones and flavanones, and the arylation of a preformed chromanone ring. In leguminous plants, the major isoflavonoids are produced via two branches of the isoflavonoid biosynthetic pathway, and the different branches share a majority of common reactions [1]. Unlike the common flavonoid compotmds, which have a 2-phenyl-benzopyrone core structure, isoflavones, such as daidzein and genistein, are 3-phenyl-benzopyrone compounds. Biochemically, the synthesis of isoflavones is an offshoot of the flavonoids biosynthesis pathway. Several attempts have aimed to increase... 

In addition, the keto acids 6.82) and 6.83) were intact precursors [a common sequence, in vivo, is phenylalanine cinnamic acid 6.82) The late stages of biosynthesis were suggested by the structure 6.88) for the naturally occurring base, septicine, i.e. that linkage between the aromatic rings of the amino acid fragments to... 

Fig. 3. Cinnamate biosynthesis from phenylalanine (8) to cinnamic acid (9) or from tyrosine (10) to coumaric acid (11). Coumarylquinic acid (12) is also...

The earliest references to cinnamic acid, cinnamaldehyde, and cinnamyl alcohol are associated with thek isolation and identification as odor-producing constituents in a variety of botanical extracts. It is now generally accepted that the aromatic amino acid L-phenylalanine [63-91-2] a primary end product of the Shikimic Acid Pathway, is the precursor for the biosynthesis of these phenylpropanoids in higher plants (1,2). 

One of the most interesting uses for cinnamic acid in recent years has been as a raw material in the preparation of L-phenylalanine [63-91-2] the key intermediate for the synthetic dipeptide sweetener aspartame (25). Genex has described a biosynthetic route to L-phenylalanine which involves treatment of immobilized ceUs of R rubra containing the enzyme phenylalanine ammonia lyase (PAT,) with ammonium cinnamate [25459-05-6] (26). 

Two of the main raw materials used for bioconversion to L-phenylalanine are frous-cinnamic acid and acetamido cinnamic add (reactions 1 and 2 in Figure 8.6.)... 

Figure A8.12 Enzymatic conversion of frans-cinnamic acid to L-phenylalanine.

Phenylalanine ammonia-lyase (PAL EC 4.3.1.5) is a pivotal enzyme in controlling flow of carbon from aromatic amino acids to secondary aromatic compounds (Figure 1) (28). PAL primarily deaminates phenylalanine to form t-cinnamic acid, however, in many species, it also less efficiently deaminates tyrosine to form -coumaric acid. Because PAL is restricted to plants and is an important enzyme in plant development, Jangaard (29) suggested that PAL inhibitors might make safe and effective herbicides, however, in his screen of several herbicides, he found no compound to have a specific effect on PAL. This was also the case in studies by Hoagland and Duke (30, 31.) in which 16 herbicides were screened. 

The key reaction that links primary and secondary metabolism is provided by the enzyme phenylalanine ammonia lyase (PAL) which catalyzes the deamination of l-phenylalanine to form iran.v-cinnamic acid with the release of NH3 (see Fig. 3.3). Tyrosine is similarly deaminated by tyrosine ammonia lyase (TAL) to produce 4-hydroxycinnamic acid and NH3. The released NH3 is probably fixed by the glutamine synthetase reaction. These deaminations initiate the main phenylpropanoid pathway. 

Lignin has a complex structure that varies with the source, growing conditions, etc. This complex and varied structure is typical of many plant-derived macromolecules. Lignin is generally considered as being formed from three different phenylpropanoid alcohols— coniferyl, coumaryl, and sinapyl alcohols, which are synthesized from phenylalanine via various cinnamic acid derivatives and commercially is sometimes treated as being composed of a Cg repeat unit where the superstructure contains aromatic and aliphatic alcohols and ethers, and aliphatic aldehydes and vinyl units. 

Phenylalanine Ammonia-Lyase. The building units of lignin are formed from carbohydrate via the shikimic acid pathway to give aromatic amino acids. Once the aromatic amino acids are formed, a key enzyme for the control of lignin precursor synthesis is phenylalanine ammonia-lyase (PAL) (1). This enzyme catalyzes the production of cinnamic acid from phenylalanine. It is very active in those tissues of the plant that become lignified and it is also a central enzyme for the production of other phenylpropanoid-derived compounds such as flavonoids and coumarins, which can occur in many parts of the plant and in many different organs (35). Radioactive phenylalanine and cinnamic acid are directly incorporated into lignin in vascular tissue (36). 

The PAL activity that is necessary for lignin formation occurs in the cytoplasm or bound to the cytoplasmic surface of the endoplasmic reticulum membranes. The cinnamic acid produced is probably carried on the lipid surface of the membranes, since it is lipophilic, and it is sequentially hydroxylated by the membrane-bound hydroxylases (47,50). In this way there is the possibility of at least a two-step channeling route from phenylalanine to p-coumaric acid. The transmethylases then direct the methyl groups to the meta positions. There is a difference between the transmethylases from angiosperms and those from gymnosperms, since with the latter... 

Until recently (43), only E-monolignols were considered to be involved in the process of lignification. This concept of exclusivity presumably arose from the following observations stereospecific deamination of phenylalanine, by phenylalanine ammonia lyase (PAL), affords E-cinnamic acid... 

A different approach to investigate active lignification during resistance reactions is provided by the determination of enzyme activities involved in lignin biosynthesis. Resistant plants are expected to be more strongly activated during or immediately preceding the resistance reaction compared to susceptible plants. Thus, phenylalanine ammonia-lyase (PAL) (43-45), cinnamic acid 4-hydroxylase (46), O-methyltransferases (44), and... 

The application of radioactive phenolic precursors—quinic acid and shikimic acid (52), phenylalanine (30,53), tyrosine (53), and cinnamic acid (30,31,53)—to infected wheat leaves led to a solvent- and alkali-resistant incorporation of radioactivity into hypersensitively reacting host cells suggesting lignin formation had occurred. 

DC194 Noe, W., and H. U. Seitz. Studies on the regulatory role of trans-cinnamic acid on the activity of the phenylalanine ammonia-lyase(pal)in suspens- DC206 ion cultures of Daucus carota L. Z Naturforsch Ser C 1983 38(5/6) ... 

L-phenylalanine trans-cinnamic acid phenylalanine ammonia lyase... 

Several biotransformation processes were developed. As an example Allelix used screening to isolate a Corymbacterium capable of converting df-acetamidocirmamic acid into L-phenylalanine. Lactate was added to the media to stimulate NADH regeneration. The key enzymes involved were cloned to increase copy numbers, the cells were used in iimnobilized form and phenylalanine recovery was facilitated by precipitation techniques. This approach was also explored by the Tanabe Co. in Japan. By contrast Cenex used the phenylalanine arrrmonia lyase activity of Rhodococcus rubra to convert irans-cinnamic acid. 

---