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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
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MetaCyc Enzyme: γ-glutamylhistamine synthetase

Species: Aplysia californica

Summary:
This enzyme has been characterized in extracts of ganglia from the marine mollusk Aplysia californica [Stein82]. Its cellular distribution in neuronal cell types was determined by activity assays. Activity was found in C2 cells and all other single nerve cell bodies tested. The results supported the hypothesis that γ-glutamylation by this enzyme functions in the inactivation of neuronally released histamine [Stein83].

The enzyme was primarily found in ganglia and nerve trunks of nerve tissue and in the connective tissue sheath surrounding the ganglion. Relatively low amounts of activity were found in aorta, heart, buccal muscle and hemolymph [Stein82].

Locations: cytosol

Gene-Reaction Schematic: ?

GO Terms:

Cellular Component: GO:0005829 - cytosol [Stein82]

Credits:
Created 26-Mar-2009 by Fulcher CA , SRI International


Enzymatic reaction of: γ-glutamylhistamine synthetase

Synonyms: γ-glutamylhistamine synthase, γ-GHA synthetase, L-glutamate:histamine ligase

EC Number: 6.3.2.18

histamine + L-glutamate + ATP <=> N-α-γ-L-glutamylhistamine + ADP + phosphate + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

Summary:
The enzyme was assayed by measuring the incorporation of 14C histamine into 14C N-α-γ-L-glutamylhistamine and identification of the product by micro-column ion-exchange chromatography, high-voltage paper electrophoresis, thin-layer chromatography and HPLC [Stein82].

Maximal in vitro synthesis of N-α-γ-L-glutamylhistamine required L-glutamate, ATP, dithiothreitol and Mg2+ [Stein82].

Cofactors or Prosthetic Groups: Mg2+ [Stein82]

Activators (Allosteric): serotonin [Stein82]

Inhibitors (Unknown Mechanism): octopamine [Stein82] , (R)-noradrenaline [Stein82] , dopamine [Stein82] , N-acetyl-serotonin [Stein82] , tyramine [Stein82] , 4-methylhistamine [Stein82] , 2-methylhistamine [Stein82] , 2-pyridylethylamine [Stein82] , butylamine [Stein82]

Kinetic Parameters:

Substrate
Km (μM)
Citations
L-glutamate
10600.0
[Stein82]
histamine
653.0
[Stein82]

T(opt): 41 °C [Stein82]

pH(opt): 8 [Stein82]


References

Stein82: Stein C, Weinreich D (1982). "An in vitro characterization of gamma-glutamylhistamine synthetase: a novel enzyme catalyzing histamine metabolism in the central nervous system of the marine mollusk, Aplysia californica." J Neurochem 38(1);204-14. PMID: 6125565

Stein83: Stein C, Weinreich D (1983). "Metabolism of histamine in the CNS of Aplysia californica: cellular distribution of gamma-glutamylhistamine synthetase." Comp Biochem Physiol C 74(1);79-83. PMID: 6132775


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Sun Dec 21, 2014, BIOCYC14A.