MetaCyc Enzyme: glutathionylspermidine amidase / glutathionylspermidine synthetase

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

Species: Crithidia fasciculata

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: ?

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:

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:

Km (μM)

Enzymatic reaction of: glutathionylspermidine synthetase

Synonyms: GSS

EC Number:

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 in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: glutathionylspermidine biosynthesis

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:

Km (μM)

pH(opt): 7.3 [Oza02]


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

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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 19.0 on Fri Oct 9, 2015, biocyc13.