Glutathione transferases (GSTs) are dimeric enzymes involved in cell detoxification versus many endogenous toxic compounds and xenobiotics. In addition, single monomers of GSTs appear to be involved in particular protein-protein interactions as in the case of the pi class GST that regulates the apoptotic process by means of a GST-c-Jun N-terminal kinase complex. Thus, the dimer-monomer transition of GSTs may have important physiological relevance, but many studies reached contrasting Conclusions both about the modality and extension of this event and about the catalytic competence of a single subunit. This paper re-examines the monomer-dimer question in light of novel experiments and old observations. Recent papers claimed the existence of a predominant monomeric and active species among pi, alpha, and mu class GSTS at 20-40 nM dilution levels, reporting dissociation constants (K-d) for dimeric GST of 5.1, 0.34, and 0.16 mu M, respectively. However, we demonstrate here that only traces of monomers could be found at these concentrations since all these enzymes display K-d valued of << 1 nM, values thousands of times lower than those reported previously. Time-resolved and steady-state fluorescence anisotropy experiments, two-photon fluorescence correlation spectroscopy, kinetic studies, and docking simulations have been used to reach such conclusions. Our results also indicate that there is no clear evidence of the existence of a fully active monomer. Conversely, many data strongly support the idea that the monomeric form is scarcely active or fully inactive.

De Luca, A., Fabrini, R., Orioni, B., Stella, L., Mei, G., Federici, G., et al. (2009). Monomer-Dimer Equilibrium in Glutathione Transferases: A Critical Re-Examination. BIOCHEMISTRY, 48(43), 10473-10482 [10.1021/bi901238t].

Monomer-Dimer Equilibrium in Glutathione Transferases: A Critical Re-Examination

De Luca, A;Orioni, B;Stella, L;Mei, G;Federici, G;Lo Bello, M
2009-01-01

Abstract

Glutathione transferases (GSTs) are dimeric enzymes involved in cell detoxification versus many endogenous toxic compounds and xenobiotics. In addition, single monomers of GSTs appear to be involved in particular protein-protein interactions as in the case of the pi class GST that regulates the apoptotic process by means of a GST-c-Jun N-terminal kinase complex. Thus, the dimer-monomer transition of GSTs may have important physiological relevance, but many studies reached contrasting Conclusions both about the modality and extension of this event and about the catalytic competence of a single subunit. This paper re-examines the monomer-dimer question in light of novel experiments and old observations. Recent papers claimed the existence of a predominant monomeric and active species among pi, alpha, and mu class GSTS at 20-40 nM dilution levels, reporting dissociation constants (K-d) for dimeric GST of 5.1, 0.34, and 0.16 mu M, respectively. However, we demonstrate here that only traces of monomers could be found at these concentrations since all these enzymes display K-d valued of << 1 nM, values thousands of times lower than those reported previously. Time-resolved and steady-state fluorescence anisotropy experiments, two-photon fluorescence correlation spectroscopy, kinetic studies, and docking simulations have been used to reach such conclusions. Our results also indicate that there is no clear evidence of the existence of a fully active monomer. Conversely, many data strongly support the idea that the monomeric form is scarcely active or fully inactive.
2009
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/10 - BIOCHIMICA
Settore CHIM/02 - CHIMICA FISICA
English
Con Impact Factor ISI
SITE-DIRECTED MUTAGENESIS; CATALYTICALLY ACTIVE MONOMER; DIGLUTATHIONYL-IRON COMPLEX; S-TRANSFERASE; NITRIC-OXIDE; SUBUNIT INTERFACE; P1-1; PI; PROTEINS; GST
De Luca, A., Fabrini, R., Orioni, B., Stella, L., Mei, G., Federici, G., et al. (2009). Monomer-Dimer Equilibrium in Glutathione Transferases: A Critical Re-Examination. BIOCHEMISTRY, 48(43), 10473-10482 [10.1021/bi901238t].
De Luca, A; Fabrini, R; Orioni, B; Stella, L; Mei, G; Federici, G; Ricci, G; Lo Bello, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/26241
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