Faizan Ahmad | Jamia Millia Islamia University, New Delhi (original) (raw)
Papers by Faizan Ahmad
Journal of Biomolecular Structure and Dynamics, 2002
Abstract It is well established that GAA/TTC base triplet expansion is the cause of degenerative ... more Abstract It is well established that GAA/TTC base triplet expansion is the cause of degenerative disorder in Freidreich's Ataxia. It is also known that these repeat sequences fold back to form the unusual intramolecular triple helix structures in DNA of the type Pyrimidine *Purine •Pyrimidine or Purine *Purine •Pyrimidine. In this paper we report on the stability of Purine *Purine•Pyrimidine intermolecular triple helix DNA containing GAA/TTC repeats under physiological conditions. Using the oligonucleotides 5′ TCGC GAA GAA GAA GAA GAA CGCT3′, 5′-AGCG TTC TTC TTC TTC TTC GCGA-3′for duplex and 5′- AAG AAG AAG AAG AAG −3′ as triplex forming strand (TFO), we have established the formation of triplex by UV-melting temperature (Tm), stoichiometry of mixing and circular dichroic spectra. This was further confirmed by gel-retardation assay. The thermodynamic parameters ΔG, ΔH and ΔS for both duplex and triplex formation were determined at different salt concentrations. The results suggest the formation of a stable intermolecular, anti—parallel triplex in GAA/TTC repeat sequences where each repeat unit contains two A*A•T and one G*G•C triplet. The therapeutic agents and TFOs, which competitively inhibit the in-vivo intra-molecular triplex by formation of a more stable inter-molecular triplex, could be used to reverse the transcription deficit in GAA/TTC expansions in Frataxin gene.
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![Research paper thumbnail of Protein stability [determination] problems](https://attachments.academia-assets.com/108632944/thumbnails/1.jpg)
](Frontiers in Molecular Biosciences
Human health depends on the correct folding of proteins, for misfolding and aggregation lead to d... more Human health depends on the correct folding of proteins, for misfolding and aggregation lead to diseases. An unfolded (denatured) protein can refold to its original folded state. How does this occur is known as the protein folding problem. One of several related questions to this problem is that how much more stable is the folded state than the unfolded state. There are several measures of protein stability. In this article, protein stability is given a thermodynamic definition and is measured by Gibbs free energy change (ΔGD0) associated with the equilibrium, native (N) conformation ↔ denatured (D) conformation under the physiological condition usually taken as dilute buffer (or water) at 25 °C. We show that this thermodynamic quantity (ΔGD0), where subscript D represents transition between N and D states, and superscript 0 (zero) represents the fact that the transition occurs in the absence of denaturant, can be neither measured nor predicted under physiological conditions. Howeve...
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Biochemical Journal, 1992
The guanidinium chloride (GdmCl) denaturation of RNAase A, lysozyme and metmyoglobin was investig... more The guanidinium chloride (GdmCl) denaturation of RNAase A, lysozyme and metmyoglobin was investigated at several pH values by using absorbance measurements at 287, 300 and 409 nm respectively. From these measurements the free-energy change on denaturation, delta Gapp., was calculated, assuming a two-state mechanism, and values of delta Gapp. at zero concentration of the denaturant were measured. For each protein all delta Gapp. values were adjusted to pH 7.00 by using the appropriate relationship between delta Gapp. and pH. Dependence of the adjusted delta Gapp. value on GdmCl concentration increases for metmyoglobin and decreases for the other two proteins as the denaturant concentration decreases. It has been shown that these are expected results if the presence of the acid-denatured state during the GdmCl denaturation of proteins is considered.
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The accuracy of the Content should not be relied upon and should be independently verified with p... more The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.
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<p><b>(A)</b> GdmCl-induced transition between N and D states at 25°C (curve 1)... more <p><b>(A)</b> GdmCl-induced transition between N and D states at 25°C (curve 1) and transition between X and D states at 56°C (curve 2). <b>(B)</b> Urea-induced transition between N and D states at 25°C (curve 1), and transition between X and D states at 56°C (curve 2). <b>(C)</b> Thermal denaturation of RNase-A in the absence of the denaturant at different pH values. The inset shows plot of Δ<i>H</i><sub>m,x</sub> versus <i>T</i><sub>m,x</sub>. <b>(D)</b> Curve 1 was drawn using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.e005" target="_blank">Eq (5)</a> with values of Δ<i>H</i><sub>m,x</sub> = 288 kJ mol<sup>-1</sup>, <i>T</i><sub>m,x</sub> = 39.5°C, Δ<i>C</i><sub>p,x</sub> = 5.14 kJ mol<sup>-1</sup> K<sup>-1</sup> given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.t002" target="_blank">Table 2</a>, and curve 2 was drawn using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.e006" target="_blank">Eq (6)</a> with values of Δ<i>H</i><sub>m,D</sub> = 293 kJ mol<sup>-1</sup>, <i>T</i><sub>m,D</sub> = 45.3°C, Δ<i>C</i><sub>p,D</sub> = 11.07 kJ mol<sup>-1</sup> K<sup>-1</sup> given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.t002" target="_blank">Table 2</a>.</p
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<p>Representative thermal denaturation curves of α-LA in the presence of the indicated conc... more <p>Representative thermal denaturation curves of α-LA in the presence of the indicated concentrations of urea, osmolytes and their mixtures at predicted ratios given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072533#pone-0072533-t002" target="_blank">Table 2</a>. To maintain clarity all data points and all transition curves are not shown.</p
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Journal of Biological Chemistry, 1985
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Journal of Biological Chemistry, 1984
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Journal of Biological Chemistry, 1983
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L.R. Singh, N.K. Poddar , T.A. Dar, S. Rahman , R. Kumar and F. Ahmad * Dr. B. R. Ambedkar Center... more L.R. Singh, N.K. Poddar , T.A. Dar, S. Rahman , R. Kumar and F. Ahmad * Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007, India Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India 110025 School of Biosciences and Biotechnology, Baba Ghulam Shah Badshah University, Rajouri, Jammu and Kashmir, India 185131 Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
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Molecules
A sedentary lifestyle or lack of physical activity increases the risk of different diseases, incl... more A sedentary lifestyle or lack of physical activity increases the risk of different diseases, including obesity, diabetes, heart diseases, certain types of cancers, and some neurological diseases. Physical exercise helps improve quality of life and reduces the risk of many diseases. Irisin, a hormone induced by exercise, is a fragmented product of FNDC5 (a cell membrane protein) and acts as a linkage between muscles and other tissues. Over the past decade, it has become clear that irisin is a molecular mimic of exercise and shows various beneficial effects, such as browning of adipocytes, modulation of metabolic processes, regulation of bone metabolism, and functioning of the nervous system. Irisin has a role in carcinogenesis; numerous studies have shown its impact on migration, invasion, and proliferation of cancer cells. The receptor of irisin is not completely known; however, in some tissues it probably acts via a specific class of integrin receptors. Here, we review research fro...
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Molecules
A sedentary lifestyle or lack of physical activity increases the risk of different diseases, incl... more A sedentary lifestyle or lack of physical activity increases the risk of different diseases, including obesity, diabetes, heart diseases, certain types of cancers, and some neurological diseases. Physical exercise helps improve quality of life and reduces the risk of many diseases. Irisin, a hormone induced by exercise, is a fragmented product of FNDC5 (a cell membrane protein) and acts as a linkage between muscles and other tissues. Over the past decade, it has become clear that irisin is a molecular mimic of exercise and shows various beneficial effects, such as browning of adipocytes, modulation of metabolic processes, regulation of bone metabolism, and functioning of the nervous system. Irisin has a role in carcinogenesis; numerous studies have shown its impact on migration, invasion, and proliferation of cancer cells. The receptor of irisin is not completely known; however, in some tissues it probably acts via a specific class of integrin receptors. Here, we review research fro...
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Biomolecules, 2021
Protein aggregation and misfolding are some of the most challenging obstacles, customarily studie... more Protein aggregation and misfolding are some of the most challenging obstacles, customarily studied for their association with amyloid pathologies. The mechanism of amyloid fibrillation development is a dynamic phenomenon involving various factors such as the intrinsic properties of protein and the physical and chemical environmental conditions. The purpose of this study was to see the thermal aggregation profile of alpha-lactalbumin (α-LA) and to delineate the effect of trehalose on its aggregation profile. α-LA was subjected to thermal aggregation at high concentrations. UV-Vis spectroscopy, a turbidity assay, intrinsic fluorescence, Rayleigh scattering and a thioflavin T (ThT) assay explained the steady outcomes that 1 M trehalose repressed α-LA aggregation in the most effective way followed by 0.75 M and 0.5 M and to a significantly lesser degree by 0.25 M. Multi spectroscopic obser Sania Bashir ations were further entrenched by microscopy. Transmission electron microscopy confir...
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Biomolecules, 2021
Protein aggregation and misfolding are some of the most challenging obstacles, customarily studie... more Protein aggregation and misfolding are some of the most challenging obstacles, customarily studied for their association with amyloid pathologies. The mechanism of amyloid fibrillation development is a dynamic phenomenon involving various factors such as the intrinsic properties of protein and the physical and chemical environmental conditions. The purpose of this study was to see the thermal aggregation profile of alpha-lactalbumin (α-LA) and to delineate the effect of trehalose on its aggregation profile. α-LA was subjected to thermal aggregation at high concentrations. UV-Vis spectroscopy, a turbidity assay, intrinsic fluorescence, Rayleigh scattering and a thioflavin T (ThT) assay explained the steady outcomes that 1 M trehalose repressed α-LA aggregation in the most effective way followed by 0.75 M and 0.5 M and to a significantly lesser degree by 0.25 M. Multi spectroscopic obser Sania Bashir ations were further entrenched by microscopy. Transmission electron microscopy confir...
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International journal of biological macromolecules, Jan 23, 2016
Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negati... more Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negative regulator of iron-uptake. The equilibrium unfolding and conformational stability of the HFE protein was examined in the presence of urea. The folding and unfolding transitions were monitored with the help of circular dichroism (CD), intrinsic fluorescence and absorption spectroscopy. Analysis of transition curves revealed that the folding of HFE is not a two-state process. However, it involved stable intermediates. Transition curves (plot of fluorescence (F346) and CD signal at 222nm (θ222) versus [Urea], the molar urea concentration) revealed a biphasic transition with midpoint (Cm) values at 2.88M and 4.95M urea. Whereas, absorption analysis shows one two-state transition centered at 2.96M. To estimate the protein stability, denaturation curves were analyzed for Gibbs free energy change in the absence of urea (ΔGD(0)) associated with the equilibrium of denaturation exist between nat...
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International journal of biological macromolecules, Jan 23, 2016
Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negati... more Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negative regulator of iron-uptake. The equilibrium unfolding and conformational stability of the HFE protein was examined in the presence of urea. The folding and unfolding transitions were monitored with the help of circular dichroism (CD), intrinsic fluorescence and absorption spectroscopy. Analysis of transition curves revealed that the folding of HFE is not a two-state process. However, it involved stable intermediates. Transition curves (plot of fluorescence (F346) and CD signal at 222nm (θ222) versus [Urea], the molar urea concentration) revealed a biphasic transition with midpoint (Cm) values at 2.88M and 4.95M urea. Whereas, absorption analysis shows one two-state transition centered at 2.96M. To estimate the protein stability, denaturation curves were analyzed for Gibbs free energy change in the absence of urea (ΔGD(0)) associated with the equilibrium of denaturation exist between nat...
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Biopolymers, Jan 5, 2015
Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in ... more Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in the iron homeostasis. Denaturation of HFE induced by guanidinium chloride (GdmCl) was measured by monitoring changes in [θ]222 (mean residue ellipticity at 222 nm), intrinsic fluorescence emission intensity at 346 nm (F346 ) and the difference absorption coefficient at 287 nm (Δε287 ) at pH 8.0 and 25°C. Coincidence of denaturation curves of these optical properties suggests that GdmCl-induced denaturation (native (N) state ↔ denatured (D) state) is a two-state process. The GdmCl-induced denaturation was found reversible in the entire concentration range of the denaturant. All denaturation curves were analyzed for ΔGD0, Gibbs free energy change associated with the denaturation equilibrium (N state ↔ D state) in the absence of GdmCl, which is a measure of HFE stability. We further performed molecular dynamics simulation for 40 ns to see the effect of GdmCl on the structural stability of H...
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Biopolymers, Jan 5, 2015
Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in ... more Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in the iron homeostasis. Denaturation of HFE induced by guanidinium chloride (GdmCl) was measured by monitoring changes in [θ]222 (mean residue ellipticity at 222 nm), intrinsic fluorescence emission intensity at 346 nm (F346 ) and the difference absorption coefficient at 287 nm (Δε287 ) at pH 8.0 and 25°C. Coincidence of denaturation curves of these optical properties suggests that GdmCl-induced denaturation (native (N) state ↔ denatured (D) state) is a two-state process. The GdmCl-induced denaturation was found reversible in the entire concentration range of the denaturant. All denaturation curves were analyzed for ΔGD0, Gibbs free energy change associated with the denaturation equilibrium (N state ↔ D state) in the absence of GdmCl, which is a measure of HFE stability. We further performed molecular dynamics simulation for 40 ns to see the effect of GdmCl on the structural stability of H...
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Journal of Biomolecular Structure and Dynamics, 2002
Abstract It is well established that GAA/TTC base triplet expansion is the cause of degenerative ... more Abstract It is well established that GAA/TTC base triplet expansion is the cause of degenerative disorder in Freidreich's Ataxia. It is also known that these repeat sequences fold back to form the unusual intramolecular triple helix structures in DNA of the type Pyrimidine *Purine •Pyrimidine or Purine *Purine •Pyrimidine. In this paper we report on the stability of Purine *Purine•Pyrimidine intermolecular triple helix DNA containing GAA/TTC repeats under physiological conditions. Using the oligonucleotides 5′ TCGC GAA GAA GAA GAA GAA CGCT3′, 5′-AGCG TTC TTC TTC TTC TTC GCGA-3′for duplex and 5′- AAG AAG AAG AAG AAG −3′ as triplex forming strand (TFO), we have established the formation of triplex by UV-melting temperature (Tm), stoichiometry of mixing and circular dichroic spectra. This was further confirmed by gel-retardation assay. The thermodynamic parameters ΔG, ΔH and ΔS for both duplex and triplex formation were determined at different salt concentrations. The results suggest the formation of a stable intermolecular, anti—parallel triplex in GAA/TTC repeat sequences where each repeat unit contains two A*A•T and one G*G•C triplet. The therapeutic agents and TFOs, which competitively inhibit the in-vivo intra-molecular triplex by formation of a more stable inter-molecular triplex, could be used to reverse the transcription deficit in GAA/TTC expansions in Frataxin gene.
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Frontiers in Molecular Biosciences
Human health depends on the correct folding of proteins, for misfolding and aggregation lead to d... more Human health depends on the correct folding of proteins, for misfolding and aggregation lead to diseases. An unfolded (denatured) protein can refold to its original folded state. How does this occur is known as the protein folding problem. One of several related questions to this problem is that how much more stable is the folded state than the unfolded state. There are several measures of protein stability. In this article, protein stability is given a thermodynamic definition and is measured by Gibbs free energy change (ΔGD0) associated with the equilibrium, native (N) conformation ↔ denatured (D) conformation under the physiological condition usually taken as dilute buffer (or water) at 25 °C. We show that this thermodynamic quantity (ΔGD0), where subscript D represents transition between N and D states, and superscript 0 (zero) represents the fact that the transition occurs in the absence of denaturant, can be neither measured nor predicted under physiological conditions. Howeve...
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Biochemical Journal, 1992
The guanidinium chloride (GdmCl) denaturation of RNAase A, lysozyme and metmyoglobin was investig... more The guanidinium chloride (GdmCl) denaturation of RNAase A, lysozyme and metmyoglobin was investigated at several pH values by using absorbance measurements at 287, 300 and 409 nm respectively. From these measurements the free-energy change on denaturation, delta Gapp., was calculated, assuming a two-state mechanism, and values of delta Gapp. at zero concentration of the denaturant were measured. For each protein all delta Gapp. values were adjusted to pH 7.00 by using the appropriate relationship between delta Gapp. and pH. Dependence of the adjusted delta Gapp. value on GdmCl concentration increases for metmyoglobin and decreases for the other two proteins as the denaturant concentration decreases. It has been shown that these are expected results if the presence of the acid-denatured state during the GdmCl denaturation of proteins is considered.
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The accuracy of the Content should not be relied upon and should be independently verified with p... more The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.
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<p><b>(A)</b> GdmCl-induced transition between N and D states at 25°C (curve 1)... more <p><b>(A)</b> GdmCl-induced transition between N and D states at 25°C (curve 1) and transition between X and D states at 56°C (curve 2). <b>(B)</b> Urea-induced transition between N and D states at 25°C (curve 1), and transition between X and D states at 56°C (curve 2). <b>(C)</b> Thermal denaturation of RNase-A in the absence of the denaturant at different pH values. The inset shows plot of Δ<i>H</i><sub>m,x</sub> versus <i>T</i><sub>m,x</sub>. <b>(D)</b> Curve 1 was drawn using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.e005" target="_blank">Eq (5)</a> with values of Δ<i>H</i><sub>m,x</sub> = 288 kJ mol<sup>-1</sup>, <i>T</i><sub>m,x</sub> = 39.5°C, Δ<i>C</i><sub>p,x</sub> = 5.14 kJ mol<sup>-1</sup> K<sup>-1</sup> given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.t002" target="_blank">Table 2</a>, and curve 2 was drawn using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.e006" target="_blank">Eq (6)</a> with values of Δ<i>H</i><sub>m,D</sub> = 293 kJ mol<sup>-1</sup>, <i>T</i><sub>m,D</sub> = 45.3°C, Δ<i>C</i><sub>p,D</sub> = 11.07 kJ mol<sup>-1</sup> K<sup>-1</sup> given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128740#pone.0128740.t002" target="_blank">Table 2</a>.</p
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<p>Representative thermal denaturation curves of α-LA in the presence of the indicated conc... more <p>Representative thermal denaturation curves of α-LA in the presence of the indicated concentrations of urea, osmolytes and their mixtures at predicted ratios given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072533#pone-0072533-t002" target="_blank">Table 2</a>. To maintain clarity all data points and all transition curves are not shown.</p
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Journal of Biological Chemistry, 1985
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Journal of Biological Chemistry, 1984
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Journal of Biological Chemistry, 1983
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L.R. Singh, N.K. Poddar , T.A. Dar, S. Rahman , R. Kumar and F. Ahmad * Dr. B. R. Ambedkar Center... more L.R. Singh, N.K. Poddar , T.A. Dar, S. Rahman , R. Kumar and F. Ahmad * Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007, India Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India 110025 School of Biosciences and Biotechnology, Baba Ghulam Shah Badshah University, Rajouri, Jammu and Kashmir, India 185131 Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
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Molecules
A sedentary lifestyle or lack of physical activity increases the risk of different diseases, incl... more A sedentary lifestyle or lack of physical activity increases the risk of different diseases, including obesity, diabetes, heart diseases, certain types of cancers, and some neurological diseases. Physical exercise helps improve quality of life and reduces the risk of many diseases. Irisin, a hormone induced by exercise, is a fragmented product of FNDC5 (a cell membrane protein) and acts as a linkage between muscles and other tissues. Over the past decade, it has become clear that irisin is a molecular mimic of exercise and shows various beneficial effects, such as browning of adipocytes, modulation of metabolic processes, regulation of bone metabolism, and functioning of the nervous system. Irisin has a role in carcinogenesis; numerous studies have shown its impact on migration, invasion, and proliferation of cancer cells. The receptor of irisin is not completely known; however, in some tissues it probably acts via a specific class of integrin receptors. Here, we review research fro...
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Molecules
A sedentary lifestyle or lack of physical activity increases the risk of different diseases, incl... more A sedentary lifestyle or lack of physical activity increases the risk of different diseases, including obesity, diabetes, heart diseases, certain types of cancers, and some neurological diseases. Physical exercise helps improve quality of life and reduces the risk of many diseases. Irisin, a hormone induced by exercise, is a fragmented product of FNDC5 (a cell membrane protein) and acts as a linkage between muscles and other tissues. Over the past decade, it has become clear that irisin is a molecular mimic of exercise and shows various beneficial effects, such as browning of adipocytes, modulation of metabolic processes, regulation of bone metabolism, and functioning of the nervous system. Irisin has a role in carcinogenesis; numerous studies have shown its impact on migration, invasion, and proliferation of cancer cells. The receptor of irisin is not completely known; however, in some tissues it probably acts via a specific class of integrin receptors. Here, we review research fro...
Bookmarks Related papers MentionsView impact
Biomolecules, 2021
Protein aggregation and misfolding are some of the most challenging obstacles, customarily studie... more Protein aggregation and misfolding are some of the most challenging obstacles, customarily studied for their association with amyloid pathologies. The mechanism of amyloid fibrillation development is a dynamic phenomenon involving various factors such as the intrinsic properties of protein and the physical and chemical environmental conditions. The purpose of this study was to see the thermal aggregation profile of alpha-lactalbumin (α-LA) and to delineate the effect of trehalose on its aggregation profile. α-LA was subjected to thermal aggregation at high concentrations. UV-Vis spectroscopy, a turbidity assay, intrinsic fluorescence, Rayleigh scattering and a thioflavin T (ThT) assay explained the steady outcomes that 1 M trehalose repressed α-LA aggregation in the most effective way followed by 0.75 M and 0.5 M and to a significantly lesser degree by 0.25 M. Multi spectroscopic obser Sania Bashir ations were further entrenched by microscopy. Transmission electron microscopy confir...
Bookmarks Related papers MentionsView impact
Biomolecules, 2021
Protein aggregation and misfolding are some of the most challenging obstacles, customarily studie... more Protein aggregation and misfolding are some of the most challenging obstacles, customarily studied for their association with amyloid pathologies. The mechanism of amyloid fibrillation development is a dynamic phenomenon involving various factors such as the intrinsic properties of protein and the physical and chemical environmental conditions. The purpose of this study was to see the thermal aggregation profile of alpha-lactalbumin (α-LA) and to delineate the effect of trehalose on its aggregation profile. α-LA was subjected to thermal aggregation at high concentrations. UV-Vis spectroscopy, a turbidity assay, intrinsic fluorescence, Rayleigh scattering and a thioflavin T (ThT) assay explained the steady outcomes that 1 M trehalose repressed α-LA aggregation in the most effective way followed by 0.75 M and 0.5 M and to a significantly lesser degree by 0.25 M. Multi spectroscopic obser Sania Bashir ations were further entrenched by microscopy. Transmission electron microscopy confir...
Bookmarks Related papers MentionsView impact
International journal of biological macromolecules, Jan 23, 2016
Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negati... more Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negative regulator of iron-uptake. The equilibrium unfolding and conformational stability of the HFE protein was examined in the presence of urea. The folding and unfolding transitions were monitored with the help of circular dichroism (CD), intrinsic fluorescence and absorption spectroscopy. Analysis of transition curves revealed that the folding of HFE is not a two-state process. However, it involved stable intermediates. Transition curves (plot of fluorescence (F346) and CD signal at 222nm (θ222) versus [Urea], the molar urea concentration) revealed a biphasic transition with midpoint (Cm) values at 2.88M and 4.95M urea. Whereas, absorption analysis shows one two-state transition centered at 2.96M. To estimate the protein stability, denaturation curves were analyzed for Gibbs free energy change in the absence of urea (ΔGD(0)) associated with the equilibrium of denaturation exist between nat...
Bookmarks Related papers MentionsView impact
International journal of biological macromolecules, Jan 23, 2016
Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negati... more Hereditary hemochromatosis factor E (HFE) is a type 1 transmembrane protein, and acts as a negative regulator of iron-uptake. The equilibrium unfolding and conformational stability of the HFE protein was examined in the presence of urea. The folding and unfolding transitions were monitored with the help of circular dichroism (CD), intrinsic fluorescence and absorption spectroscopy. Analysis of transition curves revealed that the folding of HFE is not a two-state process. However, it involved stable intermediates. Transition curves (plot of fluorescence (F346) and CD signal at 222nm (θ222) versus [Urea], the molar urea concentration) revealed a biphasic transition with midpoint (Cm) values at 2.88M and 4.95M urea. Whereas, absorption analysis shows one two-state transition centered at 2.96M. To estimate the protein stability, denaturation curves were analyzed for Gibbs free energy change in the absence of urea (ΔGD(0)) associated with the equilibrium of denaturation exist between nat...
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Biopolymers, Jan 5, 2015
Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in ... more Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in the iron homeostasis. Denaturation of HFE induced by guanidinium chloride (GdmCl) was measured by monitoring changes in [θ]222 (mean residue ellipticity at 222 nm), intrinsic fluorescence emission intensity at 346 nm (F346 ) and the difference absorption coefficient at 287 nm (Δε287 ) at pH 8.0 and 25°C. Coincidence of denaturation curves of these optical properties suggests that GdmCl-induced denaturation (native (N) state ↔ denatured (D) state) is a two-state process. The GdmCl-induced denaturation was found reversible in the entire concentration range of the denaturant. All denaturation curves were analyzed for ΔGD0, Gibbs free energy change associated with the denaturation equilibrium (N state ↔ D state) in the absence of GdmCl, which is a measure of HFE stability. We further performed molecular dynamics simulation for 40 ns to see the effect of GdmCl on the structural stability of H...
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Biopolymers, Jan 5, 2015
Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in ... more Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in the iron homeostasis. Denaturation of HFE induced by guanidinium chloride (GdmCl) was measured by monitoring changes in [θ]222 (mean residue ellipticity at 222 nm), intrinsic fluorescence emission intensity at 346 nm (F346 ) and the difference absorption coefficient at 287 nm (Δε287 ) at pH 8.0 and 25°C. Coincidence of denaturation curves of these optical properties suggests that GdmCl-induced denaturation (native (N) state ↔ denatured (D) state) is a two-state process. The GdmCl-induced denaturation was found reversible in the entire concentration range of the denaturant. All denaturation curves were analyzed for ΔGD0, Gibbs free energy change associated with the denaturation equilibrium (N state ↔ D state) in the absence of GdmCl, which is a measure of HFE stability. We further performed molecular dynamics simulation for 40 ns to see the effect of GdmCl on the structural stability of H...
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