Tryptophan decarboxylase activity

The enzyme AADC is involved in different metabolic pathways synthesizing two important neurotransmitters dopamine and serotonin [24]. AADC decarboxylates L-dihydroxy-phenylalanine to form dopamine and 5-hydroxytryptophan to produce serotonin. Tryptophan decarboxylase activity is detected in many brain neurons and non-nervous tissue cells. 

Lack of the enzyme can not be excluded as also tryptophan decarboxylase activity could not be determined in the same non-alkaloid producing cultures. 

Islas-Flores IR, Loyola-Vargas VM, Miranda-Ham ML (1994) Tryptophan decarboxylase activity in transformed roots fiorn Catharanthus roseus and its relationship to tryptamine, ajmalicine, and catharanthine accumulation during the culture cycle. In Vitro Cell Dev Biol... 

The formation of histamine, tyramine, hydroxytyramine and tryp-tamine (184) (as a result of tryptophan decarboxylase activity) is easily demonstrated pharmacologically through the action of these amines on blood pressure. Histamine lowers the blood pressure of cats, whereas the other... 

Decarboxylation of histidine to histamine is catalyzed by a broad-specificity aromatic L-amino acid decarboxylase that also catalyzes the decarboxylation of dopa, 5-hy-droxytryptophan, phenylalanine, tyrosine, and tryptophan. a-Methyl amino acids, which inhibit decarboxylase activity, find appfication as antihypertensive agents. Histidine compounds present in the human body include ergothioneine, carnosine, and dietary anserine (Figure 31-2). Urinary levels of 3-methylhistidine are unusually low in patients with Wilson s disease. 

Hotchkiss, A.J. Morgan, M.E. and Gibb, J.W. The long-term effects of multiple doses of methamphetamine on neostriatal tryptophan hydroxylase, tyrosine hydroxylase, choline acetyltransferase and glutamate decarboxylase activities. Life Sci 25 1373-1378. 1979. 

EILERT, U., DE LUCA, V., CONSTABEL, F., KURZ, W.G.W., Elicitor-mediated induction of tryptophan decarboxylase and strictosidine synthase activities in cell suspension cultures of Catharanthus roseus. Arch Biochem. Biophys., 1987, 254,491-497. 

Tryptophan s effect on cell proliferation and ornithine decarboxylase activity — The role of increased cell proliferation in the process of carcinogenesis has merited much attention.302 However, whether the presence of... 

Matsuschima, M., Takano, S., Erturk, E., and Bryan, G. T., Induction of ornithine decarboxylase activity in mouse urinary bladder by L-tryptophan and some of its metabolites, Cancer Res., 42, 3587, 1982. 

Fig (2). Aromatic L-amino acid decarboxylase also known as tryptophan decarboxylase, catalyses the synthesis of 5-bydnoxyiriplaminc (serotonin) from 5-hydroxytryptophan. lire reaction consists of a decarboxylation activity that is found in many human tissue cells... 

Chaudhuri, J., Martin, R. E. and Donahue, M. J. (1988) Tryptophan hydroxylase and aromatic L-amino acid decarboxylase activities in the tissues of adult Ascaris suum. Int. J. Parasitol. 18 341-346. 

The most importaiit enzymes on this model are TDC (tryptophan decarboxylase), GlOH (geraniol 10-hydroxylase) and SS (strictoside symthase). NADPH, PO (peroxidase), O (oxidase), and NADlf are all active in different Catharantus alkaloid formations. The biochemical models are subject to both qualitative and quantitative alkaloid analysis. Not all enzymes par-tieipating in alkaloid symthesis and degradation are yet known. Alkaloid enzymatology is, therefore, a growing research area. 

---