Papers by Mohammad Furkan
Journal of Molecular Liquids, 2022
International Journal of Biological Macromolecules, 2022
The present article reports the biogenic synthesis of silver nanoparticles (AgNPs) and gold nanop... more The present article reports the biogenic synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) from the extract of Acacia auriculiformis (AA) leaves using biogenic approach. Several spectral and morphological studies namely UV-vis, Fourier transform infrared (FT-IR), tunneling electron microscopy along with selected area electron diffraction (TEM/SAED), scanning electron microscopy along with energy dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD) were carried out which ascertains the successful formation of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) starting from Silver nitrate and Chloroauric acid respectively. On the basis of TEM/SAED and SEM-EDX, AgNPs were found to be more regular with smaller particle size and hence they were selected for biological studies. Thermal techniques like thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were also performed to study the comparative thermal stability of AgNPs and AuNPs where AgNPs were found to be thermally more stable. Several biophysical techniques including Thioflavin T assay, ANS assay, Rayleigh scattering method and turbidity assay were also performed. These assays confirm that AgNPs possess better inhibitory property. Moreover, antioxidant activity of AgNPs was also carried out using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and AgNPs were found to be good antioxidant.
Journal of Molecular Liquids, 2021
Abstract Oxidative stress, amyloid formation, impaired proteasomal degradation are hallmarks of n... more Abstract Oxidative stress, amyloid formation, impaired proteasomal degradation are hallmarks of neurodegenerative diseases like Alzheimer's (AD) and are targets for developing therapeutics against such diseases. Thionamide antibiotics are second-line anti-TB drugs. We studied the inhibitory action of two thionamide drugs, prothionamide and ethionamide, against amyloid formation using various biophysical techniques. We also studied the ability of these drugs to act as antioxidants. Here, we show that both drugs are potent inhibitors of in-vitro amyloid formation of human insulin and Aβ42 and protect cultured neuroblastoma cells against the toxic effects of amyloids. Various biophysical techniques like thioflavin-T binding assays, dynamic light-scattering (DLS), circular dichroism (CD), and transmission electron microscopy studies confirm that these drugs prevent amyloid fibril formation. CD and DLS measurements reveal that these drugs exert their anti-amyloid potency by stabilising the proteins in their native state. Their cytoprotective behaviour could be attributed to their antioxidant properties and their ability to inhibit in vitro lipid peroxidation, as confirmed by various antioxidant assays. This study reports for the first time a new facet of thionamide antibiotics as potential amyloid and oxidation inhibitors, with implications in reducing oxidative stress-related manifestations of AD, thereby opening avenues to be used as a therapeutic in AD.
International Journal of Biological Macromolecules, 2021
With varying clinical symptoms, most neurodegenerative diseases are associated with abnormal loss... more With varying clinical symptoms, most neurodegenerative diseases are associated with abnormal loss of neurons. They share the same common pathogenic mechanisms involving misfolding and aggregation, and these visible aggregates of proteins are deposited in the central nervous system. Amyloid formation is thought to arise from partial unfolding of misfolded proteins leading to the exposure of hydrophobic surfaces, which interact with other similar structures and give rise to form dimers, oligomers, protofibrils, and eventually mature fibril aggregates. Accumulating evidence indicates that amyloid oligomers, not amyloid fibrils, are the most toxic species that causes Alzheimer's disease (AD) and Parkinson's disease (PD). AD has recently been recognized as the 'twenty-first century plague', with an incident rate of 1% at 60 years of age, which then doubles every fifth year. Currently, 5.3 million people in the US are afflicted with this disease, and the number of cases is expected to rise to 13.5 million by 2050. PD, a disorder of the brain, is the second most common form of dementia, characterized by difficulty in walking and movement. Keeping the above views in mind, in this review we have focused on the roles of amyloid in neurodegenerative diseases including AD and PD, the involvement of amyloid in mitochondrial dysfunction leading to neurodegeneration, are also considered in the review.
International Journal of Biological Macromolecules, 2021
Protein misfolding and aggregation can be induced by a wide variety of factors, such as dominant ... more Protein misfolding and aggregation can be induced by a wide variety of factors, such as dominant disease-associated mutations, changes in the environmental conditions (pH, temperature, ionic strength, protein concentration, exposure to transition metal ions, exposure to toxins, posttranslational modifications including glycation, phosphorylation, and sulfation). Misfolded intermediates interact with similar intermediates and progressively form dimers, oligomers, protofibrils, and fibrils. In amyloidoses, fibrillar aggregates are deposited in the tissues either as intracellular inclusion or extracellular plaques (amyloid). When such proteinaceous deposit occurs in the neuronal cells, it initiates degeneration of neurons and consequently resulting in the manifestation of various neurodegenerative diseases. Several different types of molecules have been designed and tested both in vitro and in vivo to evaluate their anti-amyloidogenic efficacies. For instance, the native structure of a protein associated with amyloidosis could be stabilized by ligands, antibodies could be used to remove plaques, oligomer-specific antibody A11 could be used to remove oligomers, or prefibrillar aggregates could be removed by affibodies. Keeping the above views in mind, in this review we have discussed protein misfolding and aggregation, mechanisms of protein aggregation, factors responsible for aggregations, and strategies for aggregation inhibition.
International Journal of Biological Macromolecules, 2021
Protein misfolding and aggregation can be induced by a wide variety of factors, such as dominant ... more Protein misfolding and aggregation can be induced by a wide variety of factors, such as dominant disease-associated mutations, changes in the environmental conditions (pH, temperature, ionic strength, protein concentration, exposure to transition metal ions, exposure to toxins, posttranslational modifications including glycation, phosphorylation, and sulfation). Misfolded intermediates interact with similar intermediates and progressively form dimers, oligomers, protofibrils, and fibrils. In amyloidoses, fibrillar aggregates are deposited in the tissues either as intracellular inclusion or extracellular plaques (amyloid). When such proteinaceous deposit occurs in the neuronal cells, it initiates degeneration of neurons and consequently resulting in the manifestation of various neurodegenerative diseases. Several different types of molecules have been designed and tested both in vitro and in vivo to evaluate their anti-amyloidogenic efficacies. For instance, the native structure of a protein associated with amyloidosis could be stabilized by ligands, antibodies could be used to remove plaques, oligomer-specific antibody A11 could be used to remove oligomers, or prefibrillar aggregates could be removed by affibodies. Keeping the above views in mind, in this review we have discussed protein misfolding and aggregation, mechanisms of protein aggregation, factors responsible for aggregations, and strategies for aggregation inhibition.
Journal of Molecular Structure, 2021
Materials Advances, 2021
A first report on the fabrication of nanocomposite scaffolds containing nano-hydroxyapatite/carbo... more A first report on the fabrication of nanocomposite scaffolds containing nano-hydroxyapatite/carboxymethyl chitosan/β-cyclodextrin heterojunctions fused with date seed extract for bone tissue engineering applications.
Journal of Molecular Liquids, 2020
Abstract Protein misfolding leads to several human pathologies. So far, there has not been much s... more Abstract Protein misfolding leads to several human pathologies. So far, there has not been much success on the remediations of these protein conformational disorders. Since these diseases arise as a result of protein aggregation, hence inhibition of aggregation could be a promising approach for designing new therapeutics. For which; polyphenols, antibiotics and other small compounds have been tested by the researchers in the recent past, but so far there has not been much success. Here we have investigated the effect of carminic acid over Human serum albumin in an in vitro manner. It was observed that there was severe resistance in the increment of fluorescence intensity in the presence of carminic acid when observed through ANS, ThT and RLS, which was further supported by CD and Congo red assay. Microscopic analysis also confirmed that there was aggregation inhibition in the presence of180μM carminic acid. ROS and SDS-PAGE results also established the same. Furthermore, molecular docking was performed to understand the interacting residues which were found to be Arg, Leu, Glu. It is noteworthy that inhibitory effect was concentration dependent and maximum inhibition was found to be in presence of 180 μM of carminic acid. These results shall be helpful in designing the new therapeutics against amyloidosis.
Current Protein & Peptide Science, 2020
Protein folding is a natural phenomenon through which a linear polypeptide possessing necessary i... more Protein folding is a natural phenomenon through which a linear polypeptide possessing necessary information attains three-dimension functionally active conformation. This is a complex and multistep process and therefore, the presence of several intermediary structures could be speculated as a result of protein folding. In in vivo, this folding process is governed by the assistance of other proteins called molecular chaperones and heat shock proteins. Due to the mechanism of protein folding, these intermediary structures remain major challenge for modern biology. Mutation in gene encoding amino acid can cause adverse environmental conditions which may result in misfolding of the linear polypeptide followed by the formation of aggregates and amyloidosis. Aggregation contributes to the pathophysiology of several maladies including diabetes mellitus, Huntington’s and Alzheimer’s disease. The propensity of native structure to form aggregated and fibrillar assemblies is a hallmark of amyl...
International Journal of Biological Macromolecules, 2019
, et al., An antibiotic (sulfamethoxazole) stabilizes polypeptide (human serum albumin) even unde... more , et al., An antibiotic (sulfamethoxazole) stabilizes polypeptide (human serum albumin) even under extreme condition (elevated temperature),
International Journal of Biological Macromolecules, 2019
Protein misfolding diseases are associated with human pathologies. These neurodegenerative diseas... more Protein misfolding diseases are associated with human pathologies. These neurodegenerative diseases remain challenging task for researchers because of their adverse effect on vital organs system. Lysozyme amyloidosis is also associated with multi-organ dysfunction. Hence elucidation of its folding pathway is of great importance, for which hen egg white lysozyme (HEWL) being homological to its human counterpart was taken into consideration. Here in this study we have investigated the effect of diosmin (DSN), a flavonoid over thermally aggregated HEWL. Decrease in ANS, ThT and Rayleigh scattering fluorescence intensity suggests the transition between β to α conformations. Further decrease in absorbance at 360 nm and of congo red with slight blue shift also indicated the disappearance of β sheeted structure under the under the influence of increasing concentration of DSN. These results were also supported by circular dichroism in which gradual appearance α helical structure was observed. Finally visualization under transmission electron microscopy (TEM) authenticated the maximum structural alteration in the previously formed aggregates of HEWL at 250 μM DSN. Molecular docking followed by 100 ns MD simulations help to understand the interaction mechanism of HEWL with DSN. Results suggest DSN could be a useful in the treatment of amyloid related disorders.
Journal of biomolecular structure & dynamics, Jan 30, 2017
Several mammalian proteins form pathological deposits under nonphysiological conditions that are ... more Several mammalian proteins form pathological deposits under nonphysiological conditions that are associated with many degenerative diseases. Protein aggregation is associated with aging, as well as a variety of diseases, including cystic fibrosis, amyotrophic lateral sclerosis (ALS), and hypertrophic cardiomyopathy. There is a lack of any potential anti-amyloidogenic agents and therapeutics till date. Polyphenols have been accredited with myriad biological effects. An analysis of the effects of natural agents like baicalin (BC) and gallocatechin (GC) on aggregation process can open new avenues for the treatment of protein misfolding diseases. Thus, investigation of the effects of these flavonoids on Buffalo Heart Cystatin (BHC) aggregation induced by a reactive metabolic dialdehyde, glyoxal (GO), was taken up. Results have shown that elevated concentration of GO forms aggregates of BHC, which was characterized by an increase in the ANS fluorescence intensity, an increase in ThT fluo...
International journal of biological macromolecules, Jan 7, 2017
Importance of cytochrome c arises from its involvement in apoptosis, sequence homology and conser... more Importance of cytochrome c arises from its involvement in apoptosis, sequence homology and conservedness during molecular evolution. The effect of dopamine gives the clue about the conformational changes taking place in cytochrome c, resulting in aggregation. Dopamine at 25μM concentration for 30hours resulted in cytochrome c aggregation as evident by increase in ANS, ThT binding, structural transition from α helix to β sheet and shift in congo red assay. Interestingly serotonin at 25μM concentration incubated for 60hours abrogates the aggregatory effect on cytochrome c. Fibrillation of human body cytochrome c in the presence of dopamine gives clue of natural aggregation and inhibitory effect of serotonin gives the clue about natural defence mechanism occurring human body.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017
Aloe emodin, an anthroquinone from Aloe vera acts as an anti aggregatory agent to the thermally a... more Aloe emodin, an anthroquinone from Aloe vera acts as an anti aggregatory agent to the thermally aggregated hemoglobin.
Journal of fluorescence, 2016
The propensity of native state to form aggregated and fibrillar assemblies is a hallmark of amylo... more The propensity of native state to form aggregated and fibrillar assemblies is a hallmark of amyloidosis. Our study was focused at analyzing the aggregation and fibrillation tendency of cytochrome c in presence of an organic solvent i.e. acetonitrile. In vitro analysis revealed that the interaction of cytochrome c with acetonitrile facilitated the oligomerization of cytochrome c via the passage through an intermediate state which was obtained at 20 % v/v concentration of acetonitrile featured by a sharp hike in the ANS fluorescence intensity with a blue shift of 20 nm compared to the native state. Oligomers and fibrils were formed at 40 and 50 % v/v concentration respectively as indicated by a significant hike in the ThT fluorescence intensity, red shift of 55 nm in congo red binding assay and an increase in absorbance at 350 nm. They possess β-sheet structure as evident from appearance of peak at 217 nm. Finally, authenticity of oligomeric and fibrillar species was confirmed by TEM ...
Journal of biomolecular structure & dynamics, Feb 2, 2017
Catalase, a ubiquitous enzyme of the free radical scavenging machinery unfolds and aggregates in ... more Catalase, a ubiquitous enzyme of the free radical scavenging machinery unfolds and aggregates in the presence of 2, 2, 2, triflouroethanol (TFE). Catalase molecule aggregates at 50% TFE as evident by high thioflavin T fluorescence, shifted congo red absorbance, change in circular dichroism and soret spectra. TEM images confirmed the nature of catalase aggregates to be oligomers. Organic solvent induced aggregation of catalase is prevented by presence of peroxidase (another enzyme of the free radical scavenging machinery). To alter the progress of the aggregation in presence of increasing concentration of TFE, we determined the effect of peroxidase on catalase oligomerization by several different techniques, including turbidity measurement, activity assay, thioflavin T fluorescence, circular dichroism, shift in congo red absorbance, transmission electron microscopy, rayleigh scattering, soret absorption spectra and ANS fluorescence. The presence of peroxidase in the vicinity of folde...
Protein & Peptide Letters, 2016
Acetonitrile is a mild solvent, which induces b-sheet conformation in proteins. The global confor... more Acetonitrile is a mild solvent, which induces b-sheet conformation in proteins. The global conformational changes in Hb in presence of ACN were studied using intrinsic fluorescence experiments, acrylamide quenching, ANS fluorescence measurements, soret absorbance spectroscopy, fourier transform infrared spectroscopy, circular dichroism, thioflavin T and congo red assay. Molecular docking showed the binding of hydrophobic residues of Hb to ACN. Hb exists as a partially unfolded intermediate state at 30% v/v ACN. Hb aggregates were obtained at 60% v/v ACN concentration, which were further confirmed by transmission electron microscopy.
Protein & Peptide Letters, 2015
Molecular modeling deciphered the site of interaction of rifampicin in the structure of ovalbumin... more Molecular modeling deciphered the site of interaction of rifampicin in the structure of ovalbumin at a site which is surrounded by residues Glu-214, Asp-98, Pro-85, Asp-91 and Asp-47. Isothermal calorimetric analysis determined the thermodynamic parameters i.e. ΔH and ΔS which came out be -8.086 cal/mol and -131 cal/mol/deg. respectively. Ovalbumin is a secretory protein of hen oviduct, present in the human blood serum and interacts with the drug rifampicin in vivo, when administered. Simulating these conditions in vitro revealed that rifampicin induced the aggregated state at 6μM concentration which was featured by a decrease in the ANS fluorescence intensity relative to the native state while as the pre-molten and molten globule state were obtained at 3μM and 5 μM concentration of rifampicin respectively displaying a hike in the ANS fluorescence intensity. Far-UV CD analysis suggested β-sheet rich structure with negative ellipticity peak at 217nm for native ovalbumin incubated with 6μM rifampicin. Increase in absorbance at 450 nm, red shift of 50 nm in the congo red binding assay and a hike of 10 fold in the ThT fluorescence intensity compared to the native state further confirmed aggregate formation. Moreover, TEM images displayed aggregates to be spherical morphologically. Aggregates formed at 6μM rifampicin concentration were found to be cytotoxic as there was a reduction of cell viability to 28%. Thus, protein-drug interaction primarily facilitates a structural alteration in the native structure of proteins leading to their aggregation which were proved to be cytotoxic in nature.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Role of micellar environment created by Triton X-100 (TX-100) and CHAPSO on protein conformation ... more Role of micellar environment created by Triton X-100 (TX-100) and CHAPSO on protein conformation using IgG as a model system has been studied in this paper. A substantial amount of secondary structure with the reduction in constant tertiary contacts was obtained in both bovine and human IgG in the presence of 0.12 mM TX-100 where as 6 and 8 mM CHAPSO concentration was required for this type of secondary structure. Further addition of either of the detergents result in the induction of α-helix in both the IgGs as evident by helix specific peaks in the amide I region of FTIR and circular dichroism spectra. Tryptophan and 8-anilino-1-naphthalene-sulphonic acid (ANS) fluorescence confirmed changes in protein conformation upon addition of detergents. Maximum ANS binding at 0.12 mM TX-100 in both while 6 and 8 mM CHAPSO in bovine and human IgG respectively, indicate a compact ''molten-globule''-like conformation. An increase addition of these detergents results in the burial of hydrophobic patches of both IgG owing to aggregation. Presence of aggregates at 0.2 and 0.16 mM TX-100 and 8 and 9 mM CHAPSO, for bovine and human IgG respectively, was further confirmed by reduction in ANS fluorescence, dynamic light scattering study, thioflavin T fluorescence and congo red absorbance.
Uploads
Papers by Mohammad Furkan