Background: The 26kDa glutathione transferase (GST, EC 22.214.171.124) from Schistosoma japonicum (SjGST) is recognized as the major detoxification enzyme of S. japonicum, a pathogenic helminth causing schistosomiasis.
Objective: In the present study, the interaction of the chlorotriazine dye Cibacron blue 3GA (CB3GA) and its structural analogues with SjGST was investigated. The work aimed to shine light on the non-substrate ligand-binding properties of the enzyme.
Methods: Kinetic inhibition analysis, affinity labelling experiments and molecular modelling studies were employed.
Results: The results showed that CB3GA is a potent inhibitor (IC50 0.057 ± 0.003μM) towards SjGST. The enzyme was specifically and irreversibly inactivated by the dichlorotriazine-analogue of CB3GA (IC50 0.190 ± 0.024 μM), following a biphasic pseudo-first-order saturation kinetics with approximately 1 mol of inhibitor per mol of dimeric enzyme being incorporated. All other monochlorotriazine analogues behave as reversible inhibitors with lower inhibition potency (IC50 5.2-82.3 μM). Kinetic inhibition studies together with molecular modelling and molecular dynamics simulations established that the CB3GA binding site overlaps both the G- and H-sites. Both hydrophobic/polar interactions as well as steric effects have decisive roles in determining the inhibitory strength of CB3GA and its analogues.
Conclusion: The results of the present study might be useful in future drug design and development efforts towards SjGST.
Keywords: Affinity labelling; Cibacron Blue 3GA; Schistosoma japonicum; Schistosomiasis; Structure-guided drug design; Triazine dyes..
Copyright© Bentham Science Publishers; For any queries, please email at email@example.com.
Characterization of the ligandin site of maize glutathione S-transferase I.Biochem J. 2004 Sep 15;382(Pt 3):885-93. doi: 10.1042/BJ20040298. Biochem J. 2004. PMID: 15196053 Free PMC article.
X-ray structure of glutathione S-transferase from Schistosoma japonicum in a new crystal form reveals flexibility of the substrate-binding site.Acta Crystallogr Sect F Struct Biol Cryst Commun. 2005 Mar 1;61(Pt 3):263-5. doi: 10.1107/S1744309105004823. Epub 2005 Feb 24. Acta Crystallogr Sect F Struct Biol Cryst Commun. 2005. PMID: 16511012 Free PMC article.
Crystal structures of a schistosomal drug and vaccine target: glutathione S-transferase from Schistosoma japonica and its complex with the leading antischistosomal drug praziquantel.J Mol Biol. 1995 Feb 10;246(1):21-7. doi: 10.1006/jmbi.1994.0061. J Mol Biol. 1995. PMID: 7853399
The interaction of Candida boidinii formate dehydrogenase with a new family of chimeric biomimetic dye-ligands.Arch Biochem Biophys. 1995 Jan 10;316(1):169-78. doi: 10.1006/abbi.1995.1025. Arch Biochem Biophys. 1995. PMID: 7840613
Oxaloacetate decarboxylase: on the mode of interaction with substrate-mimetic affinity ligands.Arch Biochem Biophys. 1995 Aug 1;321(1):61-70. doi: 10.1006/abbi.1995.1368. Arch Biochem Biophys. 1995. PMID: 7639537