Arginine decarboxylation

Certain amino acids and their derivatives, although not found in proteins, nonetheless are biochemically important. A few of the more notable examples are shown in Figure 4.5. y-Aminobutyric acid, or GABA, is produced by the decarboxylation of glutamic acid and is a potent neurotransmitter. Histamine, which is synthesized by decarboxylation of histidine, and serotonin, which is derived from tryptophan, similarly function as neurotransmitters and regulators. /3-Alanine is found in nature in the peptides carnosine and anserine and is a component of pantothenic acid (a vitamin), which is a part of coenzyme A. Epinephrine (also known as adrenaline), derived from tyrosine, is an important hormone. Penicillamine is a constituent of the penicillin antibiotics. Ornithine, betaine, homocysteine, and homoserine are important metabolic intermediates. Citrulline is the immediate precursor of arginine. 

To accommodate this new finding and the previous results, we considered a new pathway (Scheme 3), in which acetate or its derivative condenses with arginine followed by decarboxylation. Such Claisen-type condensation on alpha-amino acid has some precedent in biochemical systems (6). To prove this hypothesis, we synthesized [2- C, 2-arginine and ornithine and fed to A, flos-aquae (5). 

Vitamin Ba (pyridoxine, pyridoxal, pyridoxamine) like nicotinic acid is a pyridine derivative. Its phosphorylated form is the coenzyme in enzymes that decarboxylate amino acids, e.g., tyrosine, arginine, glycine, glutamic acid, and dihydroxyphenylalanine. Vitamin B participates as coenzyme in various transaminations. It also functions in the conversion of tryptophan to nicotinic acid and amide. It is generally concerned with protein metabolism, e.g., the vitamin B8 requirement is increased in rats during increased protein intake. Vitamin B6 is also involved in the formation of unsaturated fatty acids. 

Polyamines such as spermine and spermidine, involved in DNA packaging, are derived from methionine and ornithine by the pathway shown in Figure 22-30. The first step is decarboxylation of ornithine, a precursor of arginine (Fig. 22-10). Ornithine decarboxylase, a PLP-requiring enzyme, is the target of several powerful inhibitors used as pharmaceutical agents (Box 22-2). ... 

Degradation of L-arginine by Streptomyces griseus is initiated by a hydroxylase that causes decarboxylation and conversion of the amino acid into an amide (Eq. 24-26), a reaction analogous to that catalyzed by the flavin-dependent lysine oxygenase (Eq. 18-41). The... 

Schiff base. An alternative sequence to putrescine starting from arginine also operates concurrently as indicated in Figure 6.2. The arginine pathway also involves decarboxylation, but requires additional hydrolysis reactions to cleave the guanidine portion. 

The decarboxylation of diacyl peroxides was also used in the synthesis of a nonapeptide 148 and 5-methyl L-arginine 151 (Scheme 2.35) [65,66]. The peptide 148 is an analogue of an oxytocin receptor antagonist. The photolysis of precursor 146 gave 34% of product 147, which was reprotected with Fmoc and then incorporated into the oligopeptide. 5-Methyl arginine 151 was synthesized as a probe to study the nitric oxide synthase (NOS) active site and mechanism. The photolysis of 149 gave 150... 

Arginine decarboxylase (ADC) catalyzed decarboxylation of arginine is the initial step in an alternative pathway to putrescine in bacteria and higher plants. a-Difluoro-methylarginine (DFMA) (110)17 is an effective mechanism-based inhibitor of ADC and has been used to study compensatory processes involving ADC and ODC175. 

The V-methyl -A1 -pyrrol ini um cation is the last common intermediate in both TA and nicotine biosynthesis (Fig.7.4). V-Methy 1-A1 -pyrrolinium cation formation begins with the decarboxylation of ornithine and arginine by ornithine decarboxylase (ODC) and arginine decarboxylase (ADC), respectively. Putrescine is formed... 

Alanine and aspartic acid are produced commercially utilizing enzymes. In the case of alanine, the process of decarboxylation of aspartic acid by the aspartate decarboxylase from Pseudomonas dacunhae is commercialized. The annual world production of alanine is about 200 tons. Aspartic acid is produced commercially by condensing fumarate and ammonia using aspartase from Escherichia coli. This process has been made more convenient with an enzyme immobilization technique. Aspartic acid is used primarily as a raw material with phenylalanine to produce aspartame, a noncaloric sweetener. Production and sales of aspartame have increased rapidly since its introduction in 1981. Tyrosine, valine, leucine, isoleucine, serine, threonine, arginine, glutamine, proline, histidine, cit-rulline, L-dopa, homoserine, ornithine, cysteine, tryptophan, and phenylalanine also can be produced by enzymatic methods. 

Also of general importance is a hypothesis by Dunathan concerning the steric requirements for decarboxylation at the Ca142,143. According to this hypothesis, that sp3 hybrid at the Ca which is part of the scissile bond is aligned perpendicular to the plane of the quinonoidal iminium, so that the incipient 2p-orbital at Ca can maximally overlap with the n system of the pyridoxal imine. This conformation requirement is outlined in 21 for the decarboxylation of arginine. 

The assay described for amino acid decarboxylase can be used to quantitate the substrates and products associated with the decarboxylation of arginine, aspartate, 2,6-diaminopimelate, histidine, glutamate, lysine, and ornithine. 

AGM (decarboxylated arginine), an endogenous amine derived from arginine and its biosynthetic enzyme (arginine decarboxylase), is broadly distributed in the CNS, including the SDH (Li et al., 1994a Raasch et al., 1995 Reis and Regunathan,... 

Tropane alkaloid biosynthesis has been studied at the biochemical level, and several enzymes from the biosynthetic pathway have been isolated and cloned, although the pathway has not been elncidated completely at the genetic level (Fig. 3b) (138). L-arginine is converted to the nonproteogenic amino acid L-omithine by the nrease enzyme arginase. Ornithine decarboxylase then decarboxylates ornithine to yield the diamine pntrescine. In Hyoscyamus, Duboisia, and Atropa, putrescine serves as the common precnrsor for the tropane alkaloids. 

Arginine is converted by a PLP-dependent decarboxylase to agmatine (Fig. 24-12) which is hydrolyzed to 1,4-diaminopropane. This important cell constituent is also formed by hydrolysis of arginine to ornithine (Fig 24-10) and decarboxylation of the lat-... 

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