Phenylalanine-cinnamate

Comparison of the Phenylalanine-Cinnamate Pathway in Brown-Rot and White-Rot Fungi... 

Figure 2. The phenylalanine-cinnamate pathway in the brown-rot fungus Ltntinus lepideus.

Figure 4. The L-phenylalanine-cinnamate pathway for biosynthesis and biodegradation of veratryl alcohol in the white-rot fungus Phanerochaete chrysosporium.

The phenylalanine-cinnamate pathway of the white-rot fungus P. chrysosporium is linked to lignin biodegradation by two reactions, i.e., by both Ca-C/3 bond and aromatic ring cleavages. These represent the... 

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... 

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