The TIM binding pocket includes a catalytic site (K13, H98, E165, L230, G232), the phosphate binding site (S211, G232, N233, I170), and the contiguous pocket region (E97, L162, A163,T207,Y209, F229, V231) [7]. The relative free energy of each ground state and transition state has been determined experimentally, and is displayed in the figure. The highest-ranked 7 candidates were purchased for testing in vitro. was calculated as , where is the apparent dissociation constant (IC50), [S] is the substrate (glyceraldehyde-3-phosphate) concentration, and is the Michaelis constant for TIM (0.4 mM glyceraldehyde-3-phosphate). The interactions between the inhibitor … 2. Triose-Phosphate Isomerase, antagonists & inhibitors. To date, no TIM inhibitors suitable for targeting mammalian TIM have been reported. Its catalytic site is at the dimer interface, but the four catalytic residues, Asn11, Lys13, His95 and Glu167, are from the same subunit. Compound 1 makes a good van der Waals fit, however, with 26 atoms contacting the enzyme. One serious problem with anticancer agents is the development of drug resistance. Tumors are often dependent on glycolysis for energy and metabolite production (the Warburg effect). in situ magnetic resonance probes of the enzyme-bound substrates to test the question of whether … A novel strategy was developed to efficiently identify ligands that could bind this site (Figure 1). This model is supported in several ways. After a short equilibration, the complex was subjected to 200 ps molecular dynamics using the Amber force fields ff99 and gaff. Triosephosphate isomerase, glycosomal; This subpathway is part of the pathway glycolysis, which is itself part of Carbohydrate degradation. Campbell ID, Jones RB, Kiener PA, Waley SG. Compound 1 was selected to bind to a conserved region of TIM that might not mutate without loss of function. Thus compound 1 might interact only with residues required for TIM function and thus avoid drug resistance during therapy due to mutation of the target to a nonbinding, but active, state. The resulting structure of the complex shows the tetracyclic ring structure occupying the cavity comprising the substrate binding region of TIM including the active catalytic site (Figures 4 and 5). One of the two proteins purified, TPI, is shown in Fig. Protein … Almost all hits made contacts to the phosphate-binding cavity of the ligand binding site, usually with a substituted or unsubstituted benzene ring. Patterns that were observed included fragment binding to the TIM catalytic site, the absence of charged groups binding near the catalytic site, and presence of an amide group bound at the catalytic site. J Mol Appl Genet. However, it is inefficient to thoroughly search a substantial fraction of chemical space of molecules with a drug-like (large) size distribution. IN SILICO DRUG DOCKING OF PHYTO INHIBITORS AGAINST TRIOSEPHOSPHATE ISOMERASE IN PLASMODIUM FALCIPARUM Abstract. Therefore 2 may be unable to form the second hydrogen bond to Glu 165 that compound 1 makes. High resolution crystal structures of triosephosphate isomerase complexed with its suicide inhibitors: The conformational flexibility of the catalytic glutamate in its closed, liganded active site Rajaram … Autodock Vina, a docking tool, is used for molecular docking that utilizes information on conformational variability from ensembles of experimental receptor structure of Triosephosphate Isomerase. TIM is a key enzyme in glycolysis catalyzing the conversion of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate [7]. We will be providing unlimited waivers of publication charges for accepted research articles as well as case reports and case series related to COVID-19. Glycolysis inhibitors thus show promise as cancer treatments. Docking scores for ZINC database fragments with this structure yielded lower overall scores. Abstract. Entries in the database inconsistent with the fragment data were eliminated using a custom Perl script. Biochemistry 1975 , 14 (24) , 5274-5279. Compound 1 satisfied computational ADME criteria which indicate “drug-likeness” including Lipinski’s “rule of five” [26] (Table 1). The modifications we developed to efficiently carry out this screen may be useful as well to others to reduce the computational expense of virtual screening. Though the catalytic site provides hydrophilic contacts, much of the binding pocket is relatively featureless. An amide group was also compatible with an open-configuration binding site. Reagents were purchased from Sigma-Aldrich Chemical Corp. Eaazhisai K, Balaram H, Balaram P, Murthy MR: Structures of unliganded and inhibitor complexes of W168F, a Loop6 hinge mutant of Plasmodium falciparum triosephosphate isomerase: observation of an intermediate position of loop6. TPI deficiency is a rare disorder in humans characterized by a severe progressive extrapyramidal course. One can thus envisage the development of selective triosephosphate isomerase inhibitors which act on unique and essential structural features. Its catalytic site is at the dimer interface, but the four catalytic residues, Asn11, Lys13, His95 … In many cases fragment binding is determined by biophysical methods such as X-ray crystallography [24]. Triosephosphate isomerase (TIM) is an essential, highly conserved component of glycolysis. Compound 2, unlike 1, lacks a hydrogen bond donor group at position 10 on the pyrimidine ring. The stability of intermolecular contacts in the complex was confirmed by analysis of the entire trajectory with the MD visualization tool VMD. Potentially, this process could produce a therapeutic effect in addition to the effect of glycolysis inhibition per se. Candidate inhibitors were added as DMSO solutions; vehicle alone was added to controls. Trypanosomal triosephosphate isomerase was incubated with the inhibitory peptides for various times and the residual activity was determined at each time point. The binding envelope for the compound we found is completely conserved suggesting that TIM might not mutate to resistance. 2,9-Dimethyl-BC+ was the most potent inhibitor of TPI, clearly more potent than the known inhibitors. Triosephosphate isomerase: … Fragment-based strategies have been used to predict binding motifs [23]. The compound tested in vitro was racemic. 100% activity is the initial activity in the presence of dimethyl sulphoxide without peptide or incubation. Triosephosphate isomerase has been used in a study to assess changes in cardiac energy metabolic pathways in overweight rats fed a high-fat diet. However, 1 was the enantiomer identified in the screen. Trichomonas vaginalis is the protozoan parasite responsible for the most prevalent, non … The docked structure of 1 with TIM was relaxed with 200 cycles of steepest descent minimization and 300 cycles of conjugant gradient minimization. Influence of pH on the interaction of inhibitors with triosephosphate isomerase and determination of the pKa of the active-site carboxyl group. Cofilin was translocated to the plasma membrane along with triose-phosphate isomerase by the Rho activator lysophosphatidic acid but not by the p160 Rho-associated kinase inhibitor Y-27632, … Structure-based screening attempts to find ligands complementary to a target binding site using a computational approach [12–15]. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Methylglyoxal contributes to the deleterious effects of a TIM deficiency. Description. Philos Trans R Soc Lond B Biol Sci. Initial screening was at 300 μM of the test substance. Vina [18] was used as the docking software. Published by Elsevier Ltd. All rights reserved. In crystal structures of phosphorylated substrates bound to TIM, the phosphate mostly interacts via contacts with TIM backbone atoms [9]. Structure-based virtual screening has been successful with many targets, for example, [12, 14, 15, 17]. Triosephosphate isomerase (TIM) (EC 5.3.1.1) 1, 2 is a homodimeric enzyme, interconverting an α‐hydroxyketone (dihydroxyacetone phosphate, DHAP) and an α‐hydroxyaldehyde (D ‐glyceraldehyde‐3‐phosphate, D ‐GAP; Fig. The catalytic site binding was consistent with the binding patterns discovered in the fragment analysis phase of this project. Sequences were aligned using ClustalW [30]. Docking of 37,647 fragments from the ZINC database [19] with PDB:ID 1R2R chain C yielded 22 modestly high-scoring hits which were analyzed for common motifs. Some of the TIM residues that make polar contacts with the phosphate of substrate (i.e., Ser 211) interact with compound 1 via hydrophobic portions of their side chain. Figure 5 illustrates, in a coarse-grain heatmap, the discreet hydrophobic domains of the binding pocket. Triosephosphate isomerase has also been used in a study to investigate proteomic identification of carbonylated proteins in F344 rat hippocampus after 1-bromopropane exposure. 1981 Jun 26; 293 (1063):159–171. Compound 1 hydrophobicity is complementary to the hydrophobicity of pocket regions to which it is bound in Figure 4. The catalytic site exhibits two alternative configurations, as described, that exist in equilibrium. Development of bis-thiazoles as inhibitors of triosephosphate isomerase from Trypanosoma cruzi. Triosephosphate isomerase (TIM) is an essential, highly conserved component of glycolysis. This type of molecule might have the potential to inhibit or reverse aerobic glycolysis in cancer, an intriguing, but still unproven, approach to cancer chemotherapy. Glu 165 forms a hydrogen bond to H14, of the hydrogen-bearing pyrimidine ring nitrogen. The second series consisted of more hydrophobic cyclic peptides, originally designed to inhibit a hepatic transport system. Contacting residues for which the sequence was unchanged for the entire series of vertebrate proteins were classified as conserved. This involved a “double screen”: small molecules (fragments) were docked to TIM and common motifs of high-scoring Vina hits were identified. We have explored the degree of independence of the two catalytic centers, interactions between the catalytic centers and the subunit‐subunit contact sites, and different conformations of triosephosphate isomerase … 2004 Oct 22;343(3):671-84. 1982; 1 (5):419–434. None of these exerted any inhibitory effect. Thus TIM is an attractive drug target. Part of the hydrophobic region overlaps the domain that binds the substrate phosphate (Figure 5). Antiglycolytic drugs acting at various steps of the glycolysis pathway have shown potential to kill or impede tumors alone or in combination with classic drugs [2–4]. Triosephosphate isomerase (TPI) deficiency is a severe disorder characterized by a shortage of red blood cells (hemolytic anemia), neurological problems, infections, and muscle … TPI … An amide moiety could be superimposed on a model of dihydroxyacetone phosphate. The PGA molecule acts as an inhibitor by binding to the active site of the enzyme and changing the conformation of the molecule. The discovered compound may provide a scaffold for elaboration of other inhibitors. This is because helminths heavily depend on glycolysis for … This method assesses similarity of properties of candidate drugs to those of approved drugs. In addition, hydrophobic contacts were made throughout the binding site. The TIM residues contacted by compound 1 docked as above (approximation of 3.6 Angstroms or less between ligand and protein) were mapped to the sequence alignment and the conservation status of each contacting residue was determined. The first stage of the virtual screen focused on ligand fragments averaging 221 MW; the second targeted lead-like molecules with a MW averaging 296. This gene encodes an enzyme, consisting of two identical proteins, which catalyzes the isomerization of glyceraldehydes 3-phosphate (G3P) and dihydroxy-acetone phosphate (DHAP) in glycolysis and gluconeogenesis. The cell can control glucose metabolism to some extent via TP53 [5]. The high conservation of the TIM catalytic site, and its centrality in cancer, suggests that a molecule targeted to that site might provide a therapy that could escape some drug resistance mechanisms. However the structure of TIM bearing substrate analogs has been solved [9, 22]. The ZINC database [19] subsets for fragments and lead-like compounds were screened. Tumors are often dependent on glycolysis for energy and metabolite production (the Warburg effect). In retrospective, TIM can be seen to be a moderately difficult target [28] for ligand binding. Contacted Clusters. Docking of fragments produced a collection of hits with some common features. In cases where candidate structures were ambiguous, alternative charged forms or tautomers were tested as well as the original database entry. Docking and molecular dynamics (MD) suggested that the inhibitor made hydrogen bond contacts with TIM catalytic residues. This leads to formation of an enediol or enediolate stabilized by Lys13 [7]. TPI deficiency is the most severe form of a group of diseases known as glycolytic enzymopathies, which are rare genetic diseases that lead to the … One effective strategy is to identify small, low affinity molecules and then improve them or use them to find larger molecules. All of these residues were conserved in 6 vertebrate species: cow, rat, dog, chimpanzee, chicken, and zebrafish:(i)catalytic region residues: N11, K13, H95, E165, P166;(ii)active-site loop: I170;(iii)phosphate-binding site: G209, G210, S211, V212;(iv)extended pocket: L230, G232, G233, A234.This shows the contacts made by 1, all of which represented TIM residues that were completely conserved in representative mammals and other vertebrates. Triose Phosphate Isomerase (TPI or TIM) is a ubiquitous dimeric enzyme with a molecular weight of ~54 kD (27 kD per subunit) which catalyzes the reversible interconversion of the triose phosphate isomers dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate (GAP), an essential process in the glycolytic pathway. We were successful in finding one compound, with a new scaffold, that may be useful by itself or allow identification of other agents of higher affinity. We are committed to sharing findings related to COVID-19 as quickly as possible. Triosephosphate isomerase (TIM) is a perfectly evolved enzyme which very fast interconverts dihydroxyacetone phosphate and d-glyceraldehyde-3-phosphate. Tumors are often dependent on glycolysis for energy and metabolite production (the Warburg effect). We have identified phenazine and 1,2,6-thiadiazine chemotypes as novel inhibitors of TIM from T. cruzi (TcTIM). Sun, H. Zhao, Y. Tang, and M. Lan, “Discovery of novel EGFR tyrosine kinase inhibitors by structure-based virtual screening,”, D. A. Gshwend, A. C. Good, and I. D. Kuntz, “Molecular docking towards drug discovery,”, M. W. Chang, C. Ayeni, S. Breuer, and B. E. Torbett, “Virtual screening for HIV protease inhibitors: a comparison of AutoDock 4 and Vina,”, O. Trott and A. J. Olson, “Software news and update AutoDock Vina: improving the speed and accuracy of docking with a new scoring function, efficient optimization, and multithreading,”, J. J. Irwin and B. K. Shoichet, “ZINC—a free database of commercially available compounds for virtual screening,”, D. A. Biochem Biophys Res Commun. This enriched database was subjected to structure-based virtual screening, again using rabbit TIM as the target. Of drug resistance: //www.ncbi.nlm.nih.gov/entrez/ ) ” reaction of triosephosphate isomerase ( TIM ) is an,! [ 1 ] purchased compounds were 00087820, 19169090, 23625983,,! D: -glyceraldehyde-3-phosphate the National cancer Institute database of three‐dimensional molecular structures −2.0–0! Bc binds with high affinity ( e.g determined experimentally, and stored at.! Using Lipinski ’ s “ Rule of Five ” criteria [ 26 ] ( Table 1 ).The is. Are often dependent on aerobic glycolysis for energy and metabolite production ( the Warburg effect ) Table )... Scaffold for elaboration of other glycolytic enzymes new drug against trichomoniasis, new inhibitory compounds of the,... 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