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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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MetaCyc Enzyme: glutathionylspermidine amidase / glutathionylspermidine synthetase

Gene: gspS Accession Number: G-7761 (MetaCyc)

Species: Crithidia fasciculata

Summary:
Glutathionylspermidine synthetase/amidase of the trypanosome Crithidia fasciculata has been cloned, expressed in Escherichia coli, and purified to homogeneity [Oza02]. Previous failures to obtain a soluble enzyme [Tetaud98] were overcome by using a (His)6 tag.

The enzyme possesses two distinct domains, which catalyze the synthetase and amidase functions independently. The end product of the synthetase activity is glutathionylspermidine, with no ability to add a second glutathione molecule (unlike tryptothione synthetase). The amidase activity could be abolished by a single amino acid substitution, which had no effect on the synthetase activity [Oza02].

Molecular Weight of Polypeptide: 80.602 kD (from nucleotide sequence), 80.524 kD (experimental) [Oza02 ]

Relationship Links: Entrez-Nucleotide:PART-OF:U66520

Gene-Reaction Schematic: ?

MultiFun Terms: cell processes protection detoxification
metabolism biosynthesis of building blocks cofactors, small molecule carriers


Enzymatic reaction of: glutathionylspermidine amidase

Synonyms: GSP amidase, glutathionylspermidine amidohydrolase (spermidine-forming), γ-L-glutamyl-L-cysteinyl-glycine:spermidine amidase

EC Number: 3.5.1.78

glutathionylspermidine + H2O <=> glutathione + spermidine

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible.

Kinetic Parameters:

Substrate
Km (μM)
Citations
glutathionylspermidine
500.0
[Oza02]


Enzymatic reaction of: glutathionylspermidine synthetase

Synonyms: GSS

EC Number: 6.3.1.8

spermidine + glutathione + ATP <=> glutathionylspermidine + ADP + phosphate + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

The reaction is physiologically favored in the direction shown.

In Pathways: glutathionylspermidine biosynthesis

Summary:
Glutathionylspermidine synthetase catalyzes the first of two distinct ATP-dependent reactions in the synthesis of trypanothione. The enzyme also has glutathionylspermidine amidase activity [Tetaud98].

Kinetic Parameters:

Substrate
Km (μM)
Citations
glutathione
252.0
[Oza02]
ATP
114.0
[Oza02]
spermidine
59.0
[Oza02]

pH(opt): 7.3 [Oza02]


References

Oza02: Oza SL, Ariyanayagam MR, Fairlamb AH (2002). "Characterization of recombinant glutathionylspermidine synthetase/amidase from Crithidia fasciculata." Biochem J 364(Pt 3);679-86. PMID: 12049631

Tetaud98: Tetaud E, Manai F, Barrett MP, Nadeau K, Walsh CT, Fairlamb AH (1998). "Cloning and characterization of the two enzymes responsible for trypanothione biosynthesis in Crithidia fasciculata." J Biol Chem 1998;273(31);19383-90. PMID: 9677355


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 Fri Nov 28, 2014, biocyc12.