Phenylalanine decarboxylase phenylethylamine

Decarboxylation of amino acids is a typical feature of the bacterial decomposition of proteins. Both phenylethylamine and tyramine were isolated from putrid meat by Barger and Walpole (30), who considered it extremely probable that they were derived from phenylalanine and tyrosine, respectively. No cell-free preparation of phenylalanine decarboxylase appears to have been reported, but decarboxylation by a crude Streptococcus faecalis preparation provides a valuable method of phenylalanine assay (887). Bacterial tyrosine decarboxylase has been studied in detail (495), especially by Gale and co-workers (summarized in 284). It requires pyridoxal phosphate as coenzyme (26, 326, 327) and, unlike mammalian tyrosine decarboxylase, also attacks dihydroxyphenylalanine. Decarboxylation normally only occurs in acid media and is considered primarily to be a protective mechanism tending to restore the pH to neu-... 

Tyrosine decarboxylase (EC 4.1.1.25) was studied at a very early date by Belleau et al. (315, 316) and reinvestigated using more modern methods by Battersby et al. (317). These studies showed that decarboxylation to yield tyramine 312, X = OH, occurred with retention of configuration. Later work (318) showed that aromatic L-amino acid decarboxylase (EC 4.1.1.28) from Micrococcus percitreus catalyzed decarboxylation of phenylalanine 297a to phenylethylamine 312, X = H, with retention of configuration. 

Since the phenylethylamines 312 produced by these decarboxylases are substrates for systems containing dopamine jS-hydroxylase (EC 1.14.17.1), the availability of 7>R and 3S isotopically labeled samples of the aromatic amino acids has allowed the stereochemistry of the hydroxylation of dopamine 313 to yield norepinephrine 314 to be studied (Scheme 83). It was shown that the 3-pro-S hydrogen, Hg, was lost from phenylalanine 297a in the process and that the hydroxylation yielding 314 therefore occurred with retention of configuration (319). 

The aromatic BA, tyramine and (3-phenylethylamine are prodnced, respectively, by decarboxylation of tyrosine and phenylalanine by the enzyme tyrosine decarboxylase (TDC) (Landete, De las Rivas, Marcobal, Munoz, 2007 Pessione et al, 2009). TDC was purified from the strain L brevis lOEB 9809 isolated from wine (Moreno-Arribas Lonvaud-Funel, 2001 Russo et al, 2012). Lucas and Lonvaud-Funel (2002) described that in L. brevis lOEB 9809, the tyramine biosynthetic pathway is encoded by a cluster of four genes (Figure 12.2). All strains carrying the TDC cluster produce both tyramine and 3-phenylethylamine, but the levels of the latter are four to... 

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