Histidine decarboxylases

Able to form Ag salt of lower solubility than AgQ in H2O. Therefore applications in photographic processes Inhibition of histidine decarboxylase activity Antifoggant for color films Anthelmintic activity Quenching for oil composition caialj si for the industrial isomerization of cis a, (3 unsaturaied carboxylic acids rubber vul-cankzate improver... 

Synthesis. Histamine [51-45-6] 2-(4-imidazolyl)ethylarnine (1) is formed by decarboxylation of histidine by the enzyme L-histidine decarboxylase (Fig. 1). Most histamine is stored preformed in cytoplasmic granules of mast cells and basophils. In humans mast cells are found in the loose connective tissue of all organs, especially around blood and lymphatic vessels and nerves. These cells are most abundant in the organs expressing allergic diseases the skin, respiratory tract, and gastrointestinal tract. 

Histamine AND histamine antagonists). It is formed from histidine by the enzyme L-histidine decarboxylase. In the periphery, histamine is stored ia mast cells, basophils, cells of the gastric mucosa, and epidermal cells. In the CNS, histamine is released from nerve cells and acts as a neurotransmitter. The actions of histamine ate terrninated by methylation and subsequent oxidation via the enzymes histamine-/V-methyltransferase and monoamine oxidase. 

Histamine is synthesized from the amino acid histidine via the action of the specific enzyme histidine decarboxylase and can be metabolized by histamine-TV-methyl transferase or diamine oxidase. Interesting, in its role as a neurotransmitter the actions of histamine are terminated by metabolism rather than re-uptake into the pre-synaptic nerve terminals. 

Histamine is synthesised by decarboxylation of histidine, its amino-acid precursor, by the specific enzyme histidine decarboxylase, which like glutaminic acid decarboxylase requires pyridoxal phosphate as co-factor. Histidine is a poor substrate for the L-amino-acid decarboxylase responsible for DA and NA synthesis. The synthesis of histamine in the brain can be increased by the administration of histidine, so its decarboxylase is presumably not saturated normally, but it can be inhibited by a fluoromethylhistidine. No high-affinity neuronal uptake has been demonstrated for histamine although after initial metabolism by histamine A-methyl transferase to 3-methylhistamine, it is deaminated by intraneuronal MAOb to 3-methylimidazole acetic acid (Fig. 13.4). A Ca +-dependent KCl-induced release of histamine has been demonstrated by microdialysis in the rat hypothalamus (Russell et al. 1990) but its overflow in some areas, such as the striatum, is neither increased by KCl nor reduced by tetradotoxin and probably comes from mast cells. 

Figure 13.4 Histamine synthesis, metabolism and receptors. Current knowledge does not justify presentation of a schematic histaminergic synapse. (1) Histidine decarboxylase (2) histamine-A-methyltransferase (3) mono amine oxidase (MAOb)...

Tohyama, M, Tamiya, R, Inagok, N and Takagi, H (1991) Morphology of histaminergic neurons with histidine decarboxylase as a marker. In Histaminergic Neurons Morphology and Eunction (Eds Watanobe, T and Wadd, H), CRC Press, Boca Raton, FL, CRC Press, pp. 107-126. 

Takahashi H, B Kimura, M Yoshikawa, T Fuji (2003) Cloning and sequencing of the histidine decarboxylase genes of Gram-negative, histamine-producing bacteria and their application in detection and identification of these organisms in fish. Appl Environ Microbiol 69 2568-2579. 

S-adenosylmethionine carboxylase is the source of the propylamine in the polyamines spermine and spermidine. The activity of spermine synthase introduces this into spermidine and spermine, which has already been noted. It is worth pointing out that, whereas the inducible histidine decarboxylase... 

Huynh QK, EE Snell (1985) Pyruvoyl-dependent histidine decarboxylases. Preparation and amino acid sequences of the p chains of histidine decarboxylase from Clostridium perfringens and Lactobacillus buchneri. J Biol Chem 260 2798-2803. 

Kamath AV, GL Vaaler, EE Snell (1991) Pyridoxal phosphate-dependent histidine decarboxylases. Cloning, sequencing, and expression of genes from Klebsiella planticola and Enterobacter aerogenes and properties of the overexpressed enzymes. J Biol Chem 266 9432-9437. 

Martin MC, M Fernandez, DM Linares, MA Alvarez (2005) Sequencing, characterization and transcriptional analysis of the histidine decarboxylase operon on Lactobacillus buchneri. Microbiology (UK) 151 1219-1229. 

HBBS Hank s balanced salt solution HCA Hypertonic citrate H-CAM Hyaluronic acid cell adhesion molecule HDC Histidine decarboxylase... 

Histamine is synthesized in the brain from L-histidine by the enzyme histidine decarboxylase (HDC) (Fig. 2.2C). HDC can be inhibited by application of a-fluoromethylhistidine (a-FMH). Unlike serotonin and the catecholamines, no... 

Histamine, or 2(4-imidazolylethylamine, was first identified in the CNS during the early years of the twentieth century. However, HA was first given the status of a neurotransmitter in the 1970s, after biochemical studies revealed the presence of the HA-synthesizing enzyme L-histidine decarboxylase (HDC)... 

There are two distinct pools of HA in the brain (1) the neuronal pool and (2) the non-neuronal pool, mainly contributed by the mast cells. The turnover of HA in mast cells is slower than in neurons it is believed that the HA contribution from the mast cells is limited and that almost all brain histaminergic actions are the result of HA released by neurons (Haas Panula, 2003). The blood-brain barrier is impermeable to HA. HA in the brain is formed from L-histidine, an essential amino acid. HA synthesis occurs in two steps (1) neuronal uptake of L-histidine by L-amino acid transporters and (2) subsequent decarboxylation of l-histidine by a specific enzyme, L-histidine decarboxylase (E.C. 4.1.1.22). It appears that the availability of L-histidine is the rate-limiting step for the synthesis of HA. The enzyme HDC is selective for L-histidine and its activity displays circadian fluctuations (Orr Quay, 1975). HA synthesis can be reduced by inhibition of the enzyme HDC. a-Fluoromethylhistidine (a-FMH) is an irreversible and a highly selective inhibitor of HDC a single systemic injection of a-FMH (10-50 mg/kg) can produce up to 90% inhibition of HDC activity within 60-120 min (Monti, 1993). Once synthesized, HA is taken up into vesicles by the vesicular monoamine transporter and is stored until released. 

Figure 6.1 Histamine synthesis and metabolism in neurons. L-histidine is transported into neurons by the L-amino acid transporter. Once inside the neuron, L-histidine is converted into histamine by the specific enzyme histidine decarboxylase. Subsequently, histamine is taken up into vesicles by the vesicular monoamine transporter and stored there until released. In the absence of a high-affinity uptake mechanism in the brain, released histamine is rapidly degraded by histamine methyltransferase, which is located postsynaptically and in glia, to telemethylhistamine, a metabolite that does not show any histamine-like activity.

Ohtsu, H. Watanabe, T. (2003). New functions of histamine found in histidine decarboxylase gene knockout mice. Biochem. Biophys. Res. Commun. 305, 443-7. 

Ohtsu, H. et al. (2001). Mice lacking histidine decarboxylase exhibit abnormal mast cells. FEBS Lett. 502, 53-6. 

Orr, E. Quay, W. B. (1975). Hypothalamic 24-hour rhythms in histamine, histidine, decarboxylase and histamine-N-methyltransferase. Endocrinology 96, 941-5. 

Patel, B. T., Tudball, N., Wada, H. Watanabe T. (1986). Adenosine deaminase and histidine decarboxylase coexist in certain neurons of the rat brain. Neurosci. Lett. 63, 185-9. 

Takagi, H., Morishima, Y., Matsuyama, T. el al (1986). Histaminergic axons in the neostriatum and cerebral cortex of the rat a correlated light and electron microscopic immunocytochemical study using histidine decarboxylase as a marker. Brain Res. 364, 114-23. 

Takeda, N., Inagaki, S., Taguchi, Y. et al. (1984). Origins of histamine-containing fibers in the cerebral cortex of rats studied by immunohistochemistry with histidine decarboxylase as a marker and transection. Brain Res. 323, 55-63. 

Specific enzymes control histamine synthesis and breakdown 253 Several forms of histidine decarboxylase may derive from a single gene 254... 

Histamine synthesis in the brain is controlled by the availability of L-histidine and the activity of histidine decarboxylase 254 Histamine is stored within and released from neurons but a neuronal transporter for histamine has not been found 254 In the vertebrate brain, histamine metabolism occurs predominately by methylation 254... 

Biosynthesis is performed in one step by the enzyme L-histidine decarboxylase (HDC, E.C. 4.1.1.22). Histamine metabolism occurs mainly by two pathways. Oxidation is carried out by diamine oxidase (DAO, E.C. 1.4.3.6), leading to imidazole acetic acid (IAA), whereas methyla-tion is effected by histamine N-methyltransferase (HMT, E.C. 2.1.1.8), producing fe/e-methylhistamine (t-MH). IAA can exist as a riboside or ribotide conjugate. t-MH is further metabolized by monoamine oxidase (MAO)-B, producing fe/e-methylimidazole acetic acid (t-MIAA). Note that histamine is a substrate for DAO but not for MAO. Aldehyde intermediates, formed by the oxidation of both histamine and t-MH, are thought to be quickly oxidized to acids under normal circumstances. In the vertebrate CNS, histamine is almost exclusively methylated... 

FIGURE 14-3 Synthesis and metabolism of histamine. Solid lines indicate the pathways for histamine formation and catabolism in brain. Dashed lines show additional pathways that can occur outside the nervous system. HDC, histidine decarboxylase HMT, histamine methyltransferase DAO, diamine oxidase MAO, monoamine oxidase. Aldehyde intermediates, shown in brackets, have been hypothesized but not isolated. 

Histamine synthesis in the brain is controlled by the availability of L-histidine and the activity of histidine decarboxylase. Although histamine is present in plasma, it does not penetrate the blood-brain barrier, such that histamine concentrations in the brain must be maintained by synthesis. With a value of 0.1 mmol/1 for L-histidine under physiological conditions, HDC is not saturated by histidine concentrations in the brain, an observation that explains the effectiveness of large systemic doses of this amino acid in raising the concentrations of histamine in the brain. The essential amino acid L-histidine is transported into the brain by a saturable, energy-dependent mechanism [5]. Subcellular fractionation studies show HDC to be localized in cytoplasmic fractions of isolated nerve terminals, i.e. synaptosomes. 

Watanabe, T., Taguchi, Y., Shiosaka, S. etal. Distribution of the histaminergic neuron system in the central nervous system of rats a fluorescent immunohistochemical analysis with histidine decarboxylase as a marker. Brain Res. 295 13-25,1984. 

Watanabe, T., Yamatodani, A., Maeyama, K. and Wada, H. Pharmacology of a-fluoromethylhistidine, a specific inhibitor of histidine decarboxylase. Trends Pharmacol. Sci. 11 363-367,1990. 

Parmentier, R., Ohtsu, H., Djebbara-Hannas, Z., Valatx, J. L., Watanabe, T. and Lin, J. S. Anatomical, physiological, and pharmacological characteristics of histidine decarboxylase knock-out mice evidence for the role of brain histamine in behavioral and sleep-wake control. /. Neurosci. 22 7695-7711,2002. 

Dere, E., Souza-Silva, M. A., Topic, B., Spieler, R. E., Haas, H. L. and Huston, J. P. Histidine-decarboxylase knockout mice show deficient nonreinforced episodic object memory, improved negatively reinforced water-maze performance, and increased neo- and ventro-striatal dopamine turnover. Learn. Mem. 10 510-519, 2003. 

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