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Ahanger IA, Parray ZA, Raina N, Bashir S, Ahmad F, Hassan MI, Shahid M, Sharma A, Islam A. Counteraction of the cetyltrimethylammonium bromide-induced protein aggregation by Heparin: Potential impact on protein aggregation and neurodegenerative diseases using biophysical approaches. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.134714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Ahanger I, Parray ZA, Nasreen K, Ahmad F, Hassan MI, Islam A, Sharma A. Heparin Accelerates the Protein Aggregation via the Downhill Polymerization Mechanism: Multi-Spectroscopic Studies to Delineate the Implications on Proteinopathies. ACS OMEGA 2021; 6:2328-2339. [PMID: 33521471 PMCID: PMC7841943 DOI: 10.1021/acsomega.0c05638] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
Heparin is one of the members of the glycosaminoglycan (GAG) family, which has been associated with protein aggregation diseases including Alzheimer's disease, Parkinson's disease, and prion diseases. Here, we investigate heparin-induced aggregation of bovine serum albumin (BSA) using different spectroscopic techniques [absorption, 8-anilino-1-naphthalene sulfonic acid (ANS) and thioflavin T (ThT) fluorescence binding, and far- and near-UV circular dichroism]. Kinetic measurements revealed that heparin is involved in the significant enhancement of aggregation of BSA. The outcomes showed dearth of the lag phase and a considerable change in rate constant, which provides conclusive evidence, that is, heparin-induced BSA aggregation involves the pathway of the downhill polymerization mechanism. Heparin also causes enhancement of fluorescence intensity of BSA significantly. Moreover, heparin was observed to form amyloids and amorphous aggregates of BSA which were confirmed by ThT and ANS fluorescence, respectively. Circular dichroism measurements exhibit a considerable change in the secondary and tertiary structure of the protein due to heparin. In addition, binding studies of heparin with BSA to know the cause of aggregation, isothermal titration calorimetry measurements were exploited, from which heparin was observed to promote the aggregation of BSA by virtue of electrostatic interactions between positively charged amino acid residues of protein and negatively charged groups of GAG. The nature of binding of heparin with BSA is very much apparent with an appreciable heat of interaction and is largely exothermic in nature. Moreover, the Gibbs free energy change (ΔG) is negative, which indicates spontaneous nature of binding, and the enthalpy change (ΔH) and entropy change (ΔS) are also largely negative, which suggest that the interaction is driven by hydrogen bonding.
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Affiliation(s)
- Ishfaq
Ahmad Ahanger
- Department
of Chemistry, Biochemistry and Forensic Science, Amity School of Applied
Sciences, Amity University Haryana, Gurugram 122 413, India
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Zahoor Ahmad Parray
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Khalida Nasreen
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Faizan Ahmad
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Md. Imtaiyaz Hassan
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Asimul Islam
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Anurag Sharma
- Department
of Chemistry, Biochemistry and Forensic Science, Amity School of Applied
Sciences, Amity University Haryana, Gurugram 122 413, India
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Demystifying the catalytic pathway of Mycobacterium tuberculosis isocitrate lyase. Sci Rep 2020; 10:18925. [PMID: 33144641 PMCID: PMC7609661 DOI: 10.1038/s41598-020-75799-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 10/07/2020] [Indexed: 02/04/2023] Open
Abstract
Pulmonary tuberculosis, caused by Mycobacterium tuberculosis, is one of the most persistent diseases leading to death in humans. As one of the key targets during the latent/dormant stage of M. tuberculosis, isocitrate lyase (ICL) has been a subject of interest for new tuberculosis therapeutics. In this work, the cleavage of the isocitrate by M. tuberculosis ICL was studied using quantum mechanics/molecular mechanics method at M06-2X/6-31+G(d,p): AMBER level of theory. The electronic embedding approach was applied to provide a better depiction of electrostatic interactions between MM and QM regions. Two possible pathways (pathway I that involves Asp108 and pathway II that involves Glu182) that could lead to the metabolism of isocitrate was studied in this study. The results suggested that the core residues involved in isocitrate catalytic cleavage mechanism are Asp108, Cys191 and Arg228. A water molecule bonded to Mg2+ acts as the catalytic base for the deprotonation of isocitrate C(2)–OH group, while Cys191 acts as the catalytic acid. Our observation suggests that the shuttle proton from isocitrate hydroxyl group C(2) atom is favourably transferred to Asp108 instead of Glu182 with a lower activation energy of 6.2 kcal/mol. Natural bond analysis also demonstrated that pathway I involving the transfer of proton to Asp108 has a higher intermolecular interaction and charge transfer that were associated with higher stabilization energy. The QM/MM transition state stepwise catalytic mechanism of ICL agrees with the in vitro enzymatic assay whereby Asp108Ala and Cys191Ser ICL mutants lost their isocitrate cleavage activities.
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Shukla R, Shukla H, Tripathi T. Structural and energetic understanding of novel natural inhibitors of Mycobacterium tuberculosis malate synthase. J Cell Biochem 2019; 120:2469-2482. [PMID: 30206985 DOI: 10.1002/jcb.27538] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/06/2018] [Indexed: 01/24/2023]
Abstract
Persistent infection by Mycobacterium tuberculosis requires the glyoxylate shunt. This is a bypass to the tricarboxylic acid cycle in which isocitrate lyase (ICL) and malate synthase (MS) catalyze the net incorporation of carbon during mycobacterial growth on acetate or fatty acids as the primary carbon source. To identify a potential antitubercular compound, we performed a structure-based screening of natural compounds from the ZINC database (n = 1 67 740) against the M tuberculosis MS (MtbMS) structure. The ligands were screened against MtbMS, and 354 ligands were found to have better docking score. These compounds were assessed for Lipinski and absorption, distribution, metabolism, excretion, and toxicity prediction where 15 compounds were found to fit well for redocking studies. After refinement by molecular docking and drug-likeness analysis, four potential inhibitors (ZINC1483899, ZINC1754310, ZINC2269664, and ZINC15729522) were identified. These four ligands with phenyl-diketo acid were further subjected to molecular dynamics simulation to compare the dynamics and stability of the protein structure after ligand binding. The binding energy analysis was calculated to determine the intermolecular interactions. Our results suggested that the four compounds had a binding free energy of -201.96, -242.02, -187.03, and -169.02 kJ·mol-1 , for compounds with IDs ZINC1483899, ZINC1754310, ZINC2269664, and ZINC15729522, respectively. We concluded that two compounds (ZINC1483899 and ZINC1754310) displayed considerable structural and pharmacological properties and could be probable drug candidates to fight against M tuberculosis parasites.
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Affiliation(s)
- Rohit Shukla
- Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Umshing, Shillong, India
| | - Harish Shukla
- Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Umshing, Shillong, India
| | - Timir Tripathi
- Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Umshing, Shillong, India
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Shukla H, Khan SR, Shukla R, Krishnan MY, Akhtar MS, Tripathi T. Alternate pathway to ascorbate induced inhibition of Mycobacterium tuberculosis. Tuberculosis (Edinb) 2018; 111:161-169. [DOI: 10.1016/j.tube.2018.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 06/12/2018] [Accepted: 06/16/2018] [Indexed: 11/28/2022]
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