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Structural basis for 18-β-glycyrrhetinic acid as a novel non-GSH analog glyoxalase I inhibitor.

Zhang H, Huang Q, Zhai J, Zhao YN, Zhang LP, Chen YY, Zhang RW, Li Q, Hu XP - Acta Pharmacol. Sin. (2015)

Bottom Line: The crystal structure of the mGLOI-GA complex showed that the carboxyl group of GA mimicked the γ-glutamyl residue of GSH by hydrogen bonding to the glutamyl sites (residues Arg38B, Asn104B and Arg123A) in the GSH binding site of mGLOI.The extensive van der Waals interactions between GA and the surrounding residues also contributed greatly to the binding of GA and mGLOI.This work demonstrates a carboxyl group to be an important functional feature of non-GSH analog GLOI inhibitors.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmaceutical Sciences & Centre for Cellular and Structural Biology of Sun Yat-sen University, Guangzhou 510006, China.

ABSTRACT

Aim: Glyoxalase I (GLOI), a glutathione (GSH)-dependent enzyme, is overexpressed in tumor cells and related to multi-drug resistance in chemotherapy, making GLOI inhibitors as potential anti-tumor agents. But the most studied GSH analogs exhibit poor pharmacokinetic properties. The aim of this study was to discover novel non-GSH analog GLOI inhibitors and analyze their binding mechanisms.

Methods: Mouse GLOI (mGLOI) was expressed in BL21 (DE3) pLysS after induction with isopropyl-β-D-1-thiogalactopyranoside and purified using AKTA FPLC system. An in vitro mGLOI enzyme assay was used to screen a small pool of compounds containing carboxyl groups. Crystal structure of the mGLOI-inhibitor complex was determined at 2.3 Å resolution. Molecular docking study was performed using Discovery Studio 2.5 software package.

Results: A natural compound 18-β-glycyrrhetinic acid (GA) and its derivative carbenoxolone were identified as potent competitive non-GSH analog mGLOI inhibitors with Ki values of 0.29 μmol/L and 0.93 μmol/L, respectively. Four pentacyclic triterpenes (ursolic acid, oleanolic acid, betulic acid and tripterine) showed weak activities (mGLOI inhibition ratio <25% at 10 μmol/L) and other three (maslinic acid, corosolic acid and madecassic acid) were inactive. The crystal structure of the mGLOI-GA complex showed that the carboxyl group of GA mimicked the γ-glutamyl residue of GSH by hydrogen bonding to the glutamyl sites (residues Arg38B, Asn104B and Arg123A) in the GSH binding site of mGLOI. The extensive van der Waals interactions between GA and the surrounding residues also contributed greatly to the binding of GA and mGLOI.

Conclusion: This work demonstrates a carboxyl group to be an important functional feature of non-GSH analog GLOI inhibitors.

No MeSH data available.


Related in: MedlinePlus

The binding conformations of GA derived from docking by employing crystal structure of human GLOI-GIP (PDB ID: 1QIN) (A), mGLOI-MGI (PDB ID: 2ZA0) (B) and mGLOI-zopolrestat (PDB ID: 4KYH) (C) as receptor, respectively. The crystal structure of GA derived from mGLOI-GA complex for comparison is shown as yellow sticks.
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fig3: The binding conformations of GA derived from docking by employing crystal structure of human GLOI-GIP (PDB ID: 1QIN) (A), mGLOI-MGI (PDB ID: 2ZA0) (B) and mGLOI-zopolrestat (PDB ID: 4KYH) (C) as receptor, respectively. The crystal structure of GA derived from mGLOI-GA complex for comparison is shown as yellow sticks.

Mentions: To investigate why GA was not identified in the in silico screening, we performed the docking studies with three representative GLOI-inhibitor crystal structures as receptors, ie, human GLOI-GIP (GSH/Zn2+-chelated inhibitor, the predominantly adopted receptor mode in in silico screening; PDB ID: 1QIN), mGLOI-MGI (non-GSH/Zn2+-chelated inhibitor; PDB ID: 2ZA0) and mGLOI-zopolrestat (non-GSH/non-Zn2+-chelation inhibitor; PDB ID: 4KYH). The results indicated that only with the GLOI-zopolrestat structure as the receptor did the docking study produce a similar conformation of GA to that observed in the crystal structure (Figure 3).


Structural basis for 18-β-glycyrrhetinic acid as a novel non-GSH analog glyoxalase I inhibitor.

Zhang H, Huang Q, Zhai J, Zhao YN, Zhang LP, Chen YY, Zhang RW, Li Q, Hu XP - Acta Pharmacol. Sin. (2015)

The binding conformations of GA derived from docking by employing crystal structure of human GLOI-GIP (PDB ID: 1QIN) (A), mGLOI-MGI (PDB ID: 2ZA0) (B) and mGLOI-zopolrestat (PDB ID: 4KYH) (C) as receptor, respectively. The crystal structure of GA derived from mGLOI-GA complex for comparison is shown as yellow sticks.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4561975&req=5

fig3: The binding conformations of GA derived from docking by employing crystal structure of human GLOI-GIP (PDB ID: 1QIN) (A), mGLOI-MGI (PDB ID: 2ZA0) (B) and mGLOI-zopolrestat (PDB ID: 4KYH) (C) as receptor, respectively. The crystal structure of GA derived from mGLOI-GA complex for comparison is shown as yellow sticks.
Mentions: To investigate why GA was not identified in the in silico screening, we performed the docking studies with three representative GLOI-inhibitor crystal structures as receptors, ie, human GLOI-GIP (GSH/Zn2+-chelated inhibitor, the predominantly adopted receptor mode in in silico screening; PDB ID: 1QIN), mGLOI-MGI (non-GSH/Zn2+-chelated inhibitor; PDB ID: 2ZA0) and mGLOI-zopolrestat (non-GSH/non-Zn2+-chelation inhibitor; PDB ID: 4KYH). The results indicated that only with the GLOI-zopolrestat structure as the receptor did the docking study produce a similar conformation of GA to that observed in the crystal structure (Figure 3).

Bottom Line: The crystal structure of the mGLOI-GA complex showed that the carboxyl group of GA mimicked the γ-glutamyl residue of GSH by hydrogen bonding to the glutamyl sites (residues Arg38B, Asn104B and Arg123A) in the GSH binding site of mGLOI.The extensive van der Waals interactions between GA and the surrounding residues also contributed greatly to the binding of GA and mGLOI.This work demonstrates a carboxyl group to be an important functional feature of non-GSH analog GLOI inhibitors.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmaceutical Sciences & Centre for Cellular and Structural Biology of Sun Yat-sen University, Guangzhou 510006, China.

ABSTRACT

Aim: Glyoxalase I (GLOI), a glutathione (GSH)-dependent enzyme, is overexpressed in tumor cells and related to multi-drug resistance in chemotherapy, making GLOI inhibitors as potential anti-tumor agents. But the most studied GSH analogs exhibit poor pharmacokinetic properties. The aim of this study was to discover novel non-GSH analog GLOI inhibitors and analyze their binding mechanisms.

Methods: Mouse GLOI (mGLOI) was expressed in BL21 (DE3) pLysS after induction with isopropyl-β-D-1-thiogalactopyranoside and purified using AKTA FPLC system. An in vitro mGLOI enzyme assay was used to screen a small pool of compounds containing carboxyl groups. Crystal structure of the mGLOI-inhibitor complex was determined at 2.3 Å resolution. Molecular docking study was performed using Discovery Studio 2.5 software package.

Results: A natural compound 18-β-glycyrrhetinic acid (GA) and its derivative carbenoxolone were identified as potent competitive non-GSH analog mGLOI inhibitors with Ki values of 0.29 μmol/L and 0.93 μmol/L, respectively. Four pentacyclic triterpenes (ursolic acid, oleanolic acid, betulic acid and tripterine) showed weak activities (mGLOI inhibition ratio <25% at 10 μmol/L) and other three (maslinic acid, corosolic acid and madecassic acid) were inactive. The crystal structure of the mGLOI-GA complex showed that the carboxyl group of GA mimicked the γ-glutamyl residue of GSH by hydrogen bonding to the glutamyl sites (residues Arg38B, Asn104B and Arg123A) in the GSH binding site of mGLOI. The extensive van der Waals interactions between GA and the surrounding residues also contributed greatly to the binding of GA and mGLOI.

Conclusion: This work demonstrates a carboxyl group to be an important functional feature of non-GSH analog GLOI inhibitors.

No MeSH data available.


Related in: MedlinePlus