Publications by authors named "Mohd Aamir Qureshi"

4 Publications

  • Page 1 of 1

Aflatoxin B Induced Structural and Conformational Changes in Bovine Serum Albumin: A Multispectroscopic and Circular Dichroism-Based Study.

ACS Omega 2021 Jul 8;6(28):18054-18064. Epub 2021 Jul 8.

Department of Biochemistry Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India.

Aflatoxin B (AFB) is a mutagen that has been categorized as a group 1 human carcinogen by the International Agency for Research on Cancer. It is produced as a secondary metabolite by soil fungi and Here, in this study, the effect of AFB on the structure and conformation of bovine serum albumin (BSA) using multispectroscopic tools like fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, and circular dichroism spectropolarimetry has been ascertained. Ultraviolet absorption spectroscopy revealed hyperchromicity in the absorption spectra of BSA in the presence of AFB. The binding constant was calculated in the range of 10 M, by fluorescence spectroscopy suggesting moderate binding of the toxin to BSA. The study also confirms the static nature of fluorescence quenching. The stoichiometry of binding sites was found to be unity. The competing capability of warfarin for AFB was higher than ibuprofen as calculated from site marker displacement assay. Förster resonance energy transfer confirmed the high efficiency of energy transfer from BSA to AFB. Circular dichroism spectropolarimetry showed a decrease in the α-helix in BSA in the presence of AFB. The melting temperature of BSA underwent an increment in the presence of a mycotoxin from 62.5 to 70.3 °C. Molecular docking confirmed the binding of AFB to subdomain IIA in BSA.
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http://dx.doi.org/10.1021/acsomega.1c01799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8296610PMC
July 2021

Ampicillin-augmented silver nanoparticles for synergistic antimicrobial response: A promising therapeutic approach.

Curr Pharm Biotechnol 2021 Jan 18. Epub 2021 Jan 18.

Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh-202002. India.

Aims: Globally Scientists are working to find more efficient antimicrobial drugs to treat microbial infections and kill drug-resistant bacteria.

Background: Despite the availability of numerous antimicrobial drugs bacterial infections still poses a serious threat to global health. Due to a constant decline in the effectiveness of antibiotics owing to their repeated exposure as well as shortlasting antimicrobial activity, led to the demand for developing novel therapeutic agents capable of controlling microbial infections.

Objective: In this study, we report antimicrobial activity of chemically synthesized silver nanoparticles (cAgNPs) augmented with ampicillin (amp) in order to increase antimicrobial response against Escherichia coli (gram -ve), Staphylococcus aureus (gram +ve) and Streptococcus mutans (gram +ve).

Methods: Nanostructure, colloidal stability, morphology and size of cAgNPs before and after functionalization were explored by UV-vis spectroscopy, FT-IR, zeta potential and TEM. The formation and functionalization of cAgNPs was confirmed from UV-vis spectroscopy and FT-IR patterns. From TEM the average sizes of cAgNPs and cAgNP-amp were found to be 13 and 7.8 nm respectively, and change in colloidal stability after augmentation was confirmed from zeta potential values. The antimicrobial efficacies of cAgNP-amp and cAgNPs against E. coli S. aureus and S. mutans were studied by determining minimum inhibitory concentrations (MICs), zone of inhibition, assessment of viable and non-viable bacterial cells and quantitative assessment of biofilm.

Results & Discussion: Our results revealed cAgNP-amp to be highly bactericidal compared to cAgNPs or amp alone. The nano-toxicity studies indicated cAgNP-amp to be less toxic compared to cAgNPs alone.

Results: This study manifested that cAgNPs show synergistic antimicrobial effect when they get functionalized with amp suggesting their application in curing long-term bacterial infections.
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http://dx.doi.org/10.2174/1389201022666210119101522DOI Listing
January 2021

Biomolecular interactions and binding dynamics of tyrosine kinase inhibitor erdafitinib, with human serum albumin.

J Biomol Struct Dyn 2021 Jul 5;39(11):3934-3947. Epub 2020 Jun 5.

Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India.

Erdafitinib is an approved tyrosine kinase inhibitor that inhibits fibroblast growth factor receptor. It has been described as one of the potent anti-tumor drugs especially for the treatment of urothelial carcinoma. In this study, we have investigated the binding dynamics of erdafitinib with human serum albumin (HSA) using multiple spectroscopic techniques. The outcome of the results suggests the occurrence of static quenching during the interaction of HSA with erdafitinib which leads to the formation of non-fluorescent HSA-erdafitinib ground state complex. Formation of HSA-erdafitinib complex was also confirmed from the findings of absorption spectral analysis. The changes in microenvironment around hydrophobic domains (especially tryptophan and tyrosine) were deciphered from fluorescence spectroscopy which was further confirmed by synchronous spectral analysis. In order to gain insight into the binding site of erdafitinib in HSA, molecular docking combined with competitive displacement assay was performed. The modified form of Stern Volmer equation was used to estimate various binding parameters including number of binding sites. The findings are indicative of a single binding site ( = 1) with binding constant in the order of 10. The negative values of thermodynamic parameters like ΔG, ΔH and ΔS were suggestive of the binding reaction being spontaneous and exothermic, while the hydrogen bonds and Van der Waals interactions being the major forces present between HSA and erdafitinib. Circular dichroism spectral analysis revealed the alterations in the conformation of HSA structure and reduction in its α-helical content.Communicated by Ramaswamy H. Sarma[Formula: see text].
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http://dx.doi.org/10.1080/07391102.2020.1772880DOI Listing
July 2021

Structural dynamics studies on the binding of aflatoxin B to chicken egg albumin using spectroscopic techniques and molecular docking.

J Biomol Struct Dyn 2020 Jul 13;38(11):3144-3155. Epub 2019 Aug 13.

Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India.

Aflatoxin B, a mycotoxin produced by large number of species including and , has been described as the most potent carcinogenic mycotoxin. In this study, we have used a multiple spectroscopic and molecular docking approach to investigate the interaction of aflatoxin B (AFB) with chicken egg albumin (CEA). Fluorescence spectroscopy, UV-Vis spectroscopy, and three-dimensional fluorescence spectroscopic techniques were employed to gain insight into the conformational changes in CEA in the presence of AFB. Fluorescence spectroscopy revealed ligand-induced quenching in the fluorescence emission spectra of CEA upon binding with AFB. Hyperchromic effect was observed in case of the ground state complex formation between CEA and AFB by UV-Vis spectroscopy. To gain further comprehension into the site of binding of AFB to CEA, competitive site marker displacement assay was performed using warfarin site marker. The magnitude of Δ value calculated from fluorescence-based method was negative which confirmed spontaneous process. The results obtained suggest that the binding is enthalpy driven and van der Waals force and hydrogen bonds are stabilizing the AFB-CEA complex. Three-dimensional fluorescence studies also confirmed the quenching in the fluorescence intensity around tryptophan residues in CEA. Circular dichroism assessment revealed reduction in the alpha helical content of CEA in the presence of AFB. Molecular docking studies showed hydrophobic interaction, van der Waals forces, and hydrogen bonds as major forces present in interaction between CEA and AFB. The overall study confirms conformational and structural alteration in the protein due to binding of AFB.Communicated by Ramaswamy H. Sarma.
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http://dx.doi.org/10.1080/07391102.2019.1652690DOI Listing
July 2020
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