Purification and properties of glutathione synthetase from bovine lens

Rathbun, William B.; Sethna, Shirley S.; Buskirk, Gale E. Van

doi:10.1016/0014-4835(77)90255-x

Cited by 21 publications

(9 citation statements)

References 18 publications

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“…With respect to the M. truncatula GSHS1, heterologous expression of gshs1 cDNA in E. coli shows that GSHS1 is a GSHS and has a high specificity for Gly. This result is in agreement with the results observed for the other eukaryotic GSHS (Mooz and Meister, 1967;Rathbun et al, 1977;Oppenheimer et al, 1979;Hell and Bergmann, 1988).…”

Section: Discussion Hgshs Specificitysupporting

confidence: 83%

“…6.3.2.23) catalyzes the addition of ␤-Ala to ␥-GC. GSHS from mammals (Rathbun et al, 1977;Oppenheimer et al, 1979), yeast (Mooz and Meister, 1967), and tobacco (Nicotiana tabacum; Hell and Bergmann, 1988) are highly specific for Gly and do not accept ␤-Ala as a substrate. In contrast, the hGSHS partially purified from shoots of V. radiata and from leaves of P. coccineus demonstrated a much higher affinity for ␤-Ala than for Gly (Macnicol, 1987;Klapheck et al, 1988).…”

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confidence: 99%

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A Medicago truncatula Homoglutathione Synthetase Is Derived from Glutathione Synthetase by Gene Duplication

et al. 2001

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Glutathione (GSH) and homo-GSH (hGSH) are the major low-molecular weight thiols synthesized in Medicago truncatula. Two M. truncatula cDNAs (gshs1 and gshs2) corresponding to a putative GSH synthetase (GSHS) and a putative hGSH synthetase (hGSHS) were characterized. Heterologous expression of gshs1 and gshs2 cDNAs in an Escherichia coli strain deficient in GSHS activity showed that GSHS1 and GSHS2 are a GSHS and an hGSHS, respectively. Leucine-534 and proline-535 present in hGSHS were substituted by alanines that are conserved in plant GSHS. These substitutions resulted in a strongly stimulated GSH accumulation in the transformed E. coli strain showing that these residues play a crucial role in the differential recognition of ␤-alanine and glycine by hGSHS. Phylogenetic analysis of GSHS2 and GSHS1 with other eukaryotic GSHS sequences indicated that gshs2 and gshs1 are the result of a gene duplication that occurred after the divergence between Fabales, Solanales, and Brassicales. Analysis of the structure of gshs1 and gshs2 genes shows they are both present in a cluster and in the same orientation in the M. truncatula genome, suggesting that the duplication of gshs1 and gshs2 occurred via a tandem duplication.

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Section: Discussion Hgshs Specificitysupporting

confidence: 83%

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confidence: 99%

A Medicago truncatula Homoglutathione Synthetase Is Derived from Glutathione Synthetase by Gene Duplication

et al. 2001

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“…However, glycine reductions of this magnitude a r e not common in the lens.The concentration of t h e y-glutamyldipeptide is not available but is probably meaningless, as this substrate is quite likely to pass directly from t h e first to this second enzyme of the reaction sequence due t o t h e apparent close association of t h e two enzymes(4).As previously mentioned, concentrations of magnesium ion and ATP must be considered together. Reported concentrations of t h e two reactants (Table 1)only approximate t h e ideal concentration relationship for this enzyme system.…”

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confidence: 98%

Lenticular glutathione synthesis: rate-limiting factors in its regulation and decline

Rathbun

1984

Current Eye Research

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Six factors were analyzed which may be involved in the decline of glutathione synthesis in the aging lens and cataract, with special emphasis placed upon the human lens. The factors included: 1) lability of gamma-glutamylcysteine synthetase, 2) paucity of gamma-glutamylcysteine synthetase in primate lenses as compared to other mammalian lenses, 3) enzyme activity reduction with age in the human lens, 4) rate control by reactant scarcity, especially of cysteine and magnesium ion, 5) rate control by inhibition using 5'-AMP, 5'-ADP and glutathione, and 6) possible dissociation of the multi-enzyme complex. It was concluded that decline of the glutathione synthetic capacity in vivo would be most likely caused by reduction of gamma-glutamylcysteine synthetase activity rather than of glutathione synthetase activity.

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“…Lens y-glutaniylcysteine synthetase is quite specific for L-glutamate, but less specific for the L-cysteine moiety [14,1S]. ATP may be substituted by GTP, or ITP, which give relative activities of 15% and 11 x, respectively [16].…”

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Bovine Lenticular γ‐Glutamylcysteine Synthetase: Reaction Sequence

Buskirk

Gander

Rathbun

1978

European Journal of Biochemistry

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The sequence of substrate addition and product release during the reaction catalyzed by y-glutamylcysteine synthetase was investigated with purified enzyme from bovine lens. Thermal inactivation and kinetic studies suggest that L-glutamate is the first substrate to bind to the enzyme. L-6-Chloroalanine was used as the L-cysteine analogue. Utilizing substrate activation and product inhibition studies, the following reaction sequence was determined : L-glutamate binding, ATP binding, ADP release, L-P-chloroalanine binding, followed by inorganic phosphate and then dipeptide release. The implications of this mechanism with regard to control of the enzyme in situ and its importance in glutathione synthesis are discussed.

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Purification and properties of glutathione synthetase from bovine lens

Cited by 21 publications

References 18 publications

A Medicago truncatula Homoglutathione Synthetase Is Derived from Glutathione Synthetase by Gene Duplication

A Medicago truncatula Homoglutathione Synthetase Is Derived from Glutathione Synthetase by Gene Duplication

Lenticular glutathione synthesis: rate-limiting factors in its regulation and decline

Bovine Lenticular γ‐Glutamylcysteine Synthetase: Reaction Sequence

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