1
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Monica P, Ranjan R, Kapoor M. Family 3 CBM improves the biochemical properties, substrate hydrolysis and coconut oil extraction by hemicellulolytic and holocellulolytic chimeras. Enzyme Microb Technol 2024; 174:110375. [PMID: 38157781 DOI: 10.1016/j.enzmictec.2023.110375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 11/10/2023] [Accepted: 12/07/2023] [Indexed: 01/03/2024]
Abstract
To understand the influence of family 3 Carbohydrate Binding Module (hereafter CBM3), single (GH5 cellulase; CelB, CelBΔCBM), bi-chimeric [GH26 endo-mannanase (ManB-1601) and GH11 endo-xylanase (XynB); ManB-XynB [1], ManB-XynB-CBM] and tri-chimeric [ManB-XynB-CelB [1], ManB-XynB-CelBΔCBM] enzyme variants (fused or deleted of CBM) were produced and purified to homogeneity. CBM3 did not alter the pH and temperature optima of bi- and tri-chimeric enzymes but improved the pH and temperature stability of ManB in CBM variants of bi-/tri-chimeric enzymes. Truncation of CBM in CelB shifted the pH optimum and increased the melting temperature (Tm 65 ℃). CBM3 improved both substrate affinity (Km) and catalytic efficiency (kcat/Km) of fused enzymes in tri-chimera and CelB but only Km for bi-chimera. Far-UV CD of CelB and bi- and tri-chimeric enzymes suggested that CBM3 improved the α-helical content and compactness in the native state but did not prevent disintegration of secondary structural contents at acidic pH. Steady-state fluorescence studies suggested that under acidic conditions CBM3 prevented the exposure of hydrophobic patches in bi-chimeric protein but could not avert the opening up of chimeric enzyme structure. Aqueous enzyme assisted treatment of mature coconut kernel using single, bi- and tri-chimeric enzymes led to cracks, peeling and fracturing of the matrix and improved the oil yield by up to 22%.
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Affiliation(s)
- P Monica
- Department of Microbiology and Fermentation Technology, CSIR-Central Food Technological Research Institute, Mysuru 570 020, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, UP, India
| | - Ritesh Ranjan
- Department of Microbiology and Fermentation Technology, CSIR-Central Food Technological Research Institute, Mysuru 570 020, India
| | - Mukesh Kapoor
- Department of Microbiology and Fermentation Technology, CSIR-Central Food Technological Research Institute, Mysuru 570 020, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, UP, India.
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2
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Anjali, Kishore N. Influence of amino acids on alkaline pH induced partially folded molten globule like intermediate of bovine serum albumin: Conformational and thermodynamic insights. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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3
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Evaluation of interactions between food colorant, tartrazine, and Apo-transferrin using spectroscopic analysis and docking simulation. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116715] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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4
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Salim MM, El Sharkasy ME, Belal F, Walash M. Multi-spectroscopic and molecular docking studies for binding interaction between fluvoxamine and human serum albumin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 252:119495. [PMID: 33524820 DOI: 10.1016/j.saa.2021.119495] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/04/2021] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
In the present study, different spectroscopic techniques have been used to study the binding interaction between the antidepressant drug fluvoxamine and human serum albumin under simulated physiological conditions (pH 7.4). The utilized spectroscopic techniques include fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, UV-Vis absorption spectroscopy, Fourier Transform Infrared spectroscopy (FT-IR), and molecular modeling methods. The obtained results revealed that the formation of a complex between human serum albumin and fluvoxamine was responsible for quenching the native fluorescence of human serum albumin. The results indicated that the quenching mechanism between human serum albumin and fluvoxamine was static. Besides, the binding constant (K), number of binding sites (n), thermodynamic parameters (ΔH, ΔS, and ΔG), and binding forces were calculated at three different temperatures (298, 310, and 318 K). These data proposed that hydrophobic forces were the principal intermolecular forces stabilizing the complex. From the molecular docking results, it could be deduced that fluvoxamine was inserted into sub-domain II A (site I) of human serum albumin and led to a slight change in human serum albumin conformation.
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Affiliation(s)
- M M Salim
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Horus University-Egypt, New Damietta 34518, Egypt.
| | - Mona E El Sharkasy
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
| | - F Belal
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
| | - M Walash
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
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5
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Pattanayak BS, Dehury B, Priyadarshinee M, Jha S, Beuria TK, Soren D, Mallick BC. Kanamycin-Mediated Conformational Dynamics of Escherichia coli Outer Membrane Protein TolC. Front Mol Biosci 2021; 8:636286. [PMID: 33937327 PMCID: PMC8083960 DOI: 10.3389/fmolb.2021.636286] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/17/2021] [Indexed: 11/13/2022] Open
Abstract
TolC is a member of the outer membrane efflux proteins (OEPs) family and acts as an exit duct to export proteins, antibiotics, and substrate molecules across the Escherichia coli cell membrane. Export of these molecules is evidenced to be brought about through the reversible interactions and binding of substrate-specific drug molecules or antibiotics with TolC and by being open for transport, which afterward leads to cross-resistance. Hence, the binding of kanamycin with TolC was monitored through molecular docking (MD), the structural fluctuations and conformational changes to the atomic level. The results were further supported from the steady-state fluorescence binding and isothermal titration calorimetry (ITC) studies. Binding of kanamycin with TolC resulted in a concentration dependent fluorescence intensity quenching with 7 nm blue shift. ITC binding data maintains a single binding site endothermic energetic curve with binding parameters indicating an entropy driven binding process. The confirmational changes resulting from this binding were monitored by a circular dichroism (CD) study, and the results showed insignificant changes in the α-helix and β-sheets secondary structure contents, but the tertiary structure shows inclusive changes in the presence of kanamycin. The experimental data substaintially correlates the RMSD, R g, and RMSF results. The resulting conformational changes of the TolC-kanamycin complexation was stabilized through H-bonding and other interactions.
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Affiliation(s)
| | - Budheswar Dehury
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Suman Jha
- Department of Life Sciences, National Institute of Technology, Rourkela, India
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6
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Urea titration of a lipase from Pseudomonas sp. reveals four different conformational states, with a stable partially folded state explaining its high aggregation propensity. Int J Biol Macromol 2021; 174:32-41. [PMID: 33508357 DOI: 10.1016/j.ijbiomac.2021.01.153] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 01/14/2021] [Accepted: 01/22/2021] [Indexed: 10/22/2022]
Abstract
The conversion of soluble proteins into amyloid fibrils has importance in protein chemistry, biology, biotechnology and medicine. A novel lipase from Pseudomonas sp. was previously shown to have an extremely high aggregation propensity. It was therefore herein studied to elucidate the physicochemical and structural determinants of this extreme behaviour. Amyloid-like structures were found to form in samples up to 2.5-3.0 M using Thioflavin T fluorescence and Congo red binding assays. However, dynamic light scattering (DLS), static light scattering and turbidimetry revealed the existence of aggregates up to 4.0 M urea, without amyloid-like structure. Two monomeric conformational states were detected with intrinsic fluorescence, 8-anilinonaphthalene-1-sulfonate (ANS) binding and circular dichroism. These were further characterized in 7.5 M and 4.5 M urea using enzymatic activity measurements, tryptophan fluorescence quenching, DLS and nuclear magnetic resonance (NMR) and were found to consist of a largely disordered and a partially folded state, respectively, with the latter appearing stable, cooperative, fairly compact, non-active, α-helical, with largely buried hydrophobic residues. The persistence of a stable structure up to high concentrations of urea, in the absence of sequence characteristics typical of a high intrinsic aggregation propensity, explains the high tendency of this enzyme to form amyloid-like structures.
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7
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Sarmah RJ, Kundu S. Structure, morphology and reversible hysteresis nature of human serum albumin (HSA) monolayer on water surface. Int J Biol Macromol 2021; 174:377-384. [PMID: 33485891 DOI: 10.1016/j.ijbiomac.2021.01.131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 12/21/2020] [Accepted: 01/19/2021] [Indexed: 11/30/2022]
Abstract
Compression-decompression surface pressure (π)-specific molecular area (A) isotherm cycle of human serum albumin (HSA) monolayer is performed on water surface at four different subphase pH conditions, i.e., below and above the isoelectric point (pI ≈ 4.7) of HSA molecule. For all pH conditions, the decompression curve nearly follows the compression curve, however, at pH ≈ 5.0, hysteresis is observed at higher surface pressure. Out-of-plane structures and in-plane morphologies obtained from the X-ray reflectivity and AFM studies show that only the film thickness variation takes place with the change in surface pressure, which is also evidenced from the BAM images. With increase in surface pressure, the oblate-shaped HSA molecules start tilting making an angle with the water surface and as the monolayer is decompressed the molecules regain their initial untilted monomolecular configuration. Depending upon the subphase pH and local surface charge of the specific protein molecule, electrostatic repulsive interaction dominates over the van der Waals attraction and as a result decompression curve follows the compression curve as the molecules repel each other, however, closer to the isoelectric point as strength of the interactions reverses, a hysteresis is obtained at higher surface pressure and accordingly monolayer behaviour modifies on the water surface.
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Affiliation(s)
- Raktim J Sarmah
- Soft Nano Laboratory, Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035, India
| | - Sarathi Kundu
- Soft Nano Laboratory, Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035, India.
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8
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Enzymatic degradation of ginkgolic acids by laccase immobilized on core/shell Fe 3O 4/nylon composite nanoparticles using novel coaxial electrospraying process. Int J Biol Macromol 2021; 172:270-280. [PMID: 33418049 DOI: 10.1016/j.ijbiomac.2021.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/29/2020] [Accepted: 01/01/2021] [Indexed: 02/06/2023]
Abstract
Enzyme immobilization can increase enzyme reusability to reduce cost of industrial production. Ginkgo biloba leaf extract is commonly used for medical purposes, but it contains ginkgolic acid, which has negative effects on human health. Here, we report a novel approach to solve the problem by degrading the ginkgolic acid with immobilized-laccase, where core/shell composite nanoparticles prepared by coaxial electrospraying might be first applied to enzyme immobilization. The core/shell Fe3O4/nylon 6,6 composite nanoparticles (FNCNs) were prepared using one-step coaxial electrospraying and can be simply recovered by magnetic force. The glutaraldehyde-treated FNCNs (FNGCNs) were used to immobilize laccase. As a result, thermal stability of the free laccase was significantly improved in the range of 60-90 °C after immobilization. The laccase-immobilized FNGCNs (L-FNGCNs) were applied to degrade the ginkgolic acids, and the rate constants (k) and times (τ50) were ~0.02 min-1 and lower than 39 min, respectively, showing good catalytic performance. Furthermore, the L-FNGCNs exhibited a relative activity higher than 0.5 after being stored for 21 days or reused for 5 cycles, showing good storage stability and reusability. Therefore, the FNGCNs carrier was a promising enzyme immobilization system and its further development and applications were of interest.
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9
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Mohammadi S, Khajeh K, Taghdir M, Ranjbar B. An experimental investigation on the influence of various buffer concentrations, osmolytes and gold nanoparticles on lysozyme: Spectroscopic and calorimetric study. Int J Biol Macromol 2021; 172:162-169. [PMID: 33412205 DOI: 10.1016/j.ijbiomac.2020.12.208] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/27/2020] [Accepted: 12/29/2020] [Indexed: 11/27/2022]
Abstract
Considering importance and several industrial applications of lysozyme, including natural antibiotic and preservative, identifier for the diagnosis of diseases, and extraction purposes, its reversibility and stability studies can be very important. In this paper, the role that buffer and osmolytes concentrations play on the thermodynamic stability of lysozyme denaturation process, that is a new simple and inexpensive method, was evaluated by Nano-DSC III, far- and near-UV CD and fluorescence techniques. In thermal denaturation study, RI and ΔG of protein increased from 25.62% to 58.82% and 48.87 to 63.63 kJ mol-1 with the increment of buffer and osmolytes concentrations, respectively. These changes showed a significant increase of 129.59% in RI and 28.16% in ΔG. The effect of buffer and osmolytes concentrations on the secondary and tertiary structures of protein was also investigated. The results indicated that increment of buffer and osmolytes concentrations increase rigidity and thermodynamic stability of protein. Also, structure of protein may be changed by its interaction with GNPs. Hence, interaction of lysozyme with GNPs was studied at the buffer and osmolytes concentrations that gives the maximum RI and ΔG, respectively. The results showed that molten globule-like state was formed by lysozyme in the presence of GNPs.
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Affiliation(s)
- Soraya Mohammadi
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
| | - Khosro Khajeh
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
| | - Majid Taghdir
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
| | - Bijan Ranjbar
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
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10
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Idakieva K, Todinova S, Dolashki A, Velkova L, Raynova Y, Dolashka P. Biophysical characterization of the structural stability of Helix lucorum hemocyanin. BIOTECHNOL BIOTEC EQ 2021. [DOI: 10.1080/13102818.2020.1837010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Krassimira Idakieva
- Department of Chemistry and Biophysics of Proteins and Enzymes, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Svetla Todinova
- Department of Biomacromolecules and Biomolecular Interactions, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Aleksandar Dolashki
- Department of Chemistry and Biophysics of Proteins and Enzymes, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Lyudmila Velkova
- Department of Chemistry and Biophysics of Proteins and Enzymes, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Yuliana Raynova
- Department of Chemistry and Biophysics of Proteins and Enzymes, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Pavlina Dolashka
- Department of Chemistry and Biophysics of Proteins and Enzymes, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
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11
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Protective actions of bioactive flavonoids chrysin and luteolin on the glyoxal induced formation of advanced glycation end products and aggregation of human serum albumin: In vitro and molecular docking analysis. Int J Biol Macromol 2020; 165:2275-2285. [PMID: 33058977 DOI: 10.1016/j.ijbiomac.2020.10.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/29/2020] [Accepted: 10/02/2020] [Indexed: 12/26/2022]
Abstract
The post-translational modification of proteins by nonenzymatic glycation (NEG) and the accumulation of AGEs are the two underlying factors associated with the long-term pathogenesis in diabetes. Glyoxal (GO) is a reactive intermediate which has the ability to modify proteins and generate AGEs at a faster rate. Human serum albumin (HSA) being the most abundant serum protein has a higher chance to be modified by NEG. The key objective of the present study is to investigate the potency of chrysin and luteolin as antiglycating and antifibrillating agents in the GO-mediated glycation and fibril formation of HSA. AGEs formation were confirmed from the absorption and fluorescence spectral measurements. Both the flavonoids were able to quench the AGEs fluorescence intensity in vitro indicating the antiglycating nature of the molecules. The formation of fibrils in the GO-modified HSA was confirmed by the Thioflavin T (ThT) fluorescence assay and the flavonoids were found to exihibit the antifibrillation properties in vitro. Docking results suggested that both the flavonoids interact with various amino acid residues of subdomain IIA including glycation prone lysines and arginines via non-covalent forces and further stabilized the structure of HSA, which further explains their mechanisms of action as antiglycating and antifibrillating agents.
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12
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Zhang C, Zhang J, Rao H, Yang J, Wang X, Peng X. Investigation on the interaction of brazilin with bovine serum albumin using multi-spectroscopic and computational methods: Exploring the binding mechanism and inhibitory effect on amyloid aggregation. Microchem J 2020. [DOI: 10.1016/j.microc.2020.105529] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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13
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Kashif M, Bharati AP, Chaturvedi SK, Khan RH, Ahmad A, Kumar B, Zamzami MA, Ahmad V, Kumari S. pH and alcohol induced structural transition in Ntf2 a nuclear transport factor of Saccharomyces cerevisiae. Int J Biol Macromol 2020; 159:79-86. [PMID: 32407943 DOI: 10.1016/j.ijbiomac.2020.05.056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 05/07/2020] [Accepted: 05/08/2020] [Indexed: 10/24/2022]
Abstract
Ntf2 is a nuclear envelope protein, which play a pivotal role in nucleocytoplasmic transport and mediates the nuclear import of RanGDP. It interacts with various nucleoporins along with Ran-GDP and part of a multicomponent system that assembles at the nuclear pore complex (NCP) during nuclear import. Here, we have described the biophysical characterization of Ntf2 from Saccharomyces cerevisiae. Recombinant Ntf2 showed increment in the β-sheet content as well as decrement in the α-helix content from pH-7.0 to pH-4.0. A subsequent decrease in the pH led to increment in the α-helical content along with decrement in β-sheet content. Intrinsic fluorescence studies demonstrated the unfolding of the protein below physiological pH. Ntf2 showed stabilization as well as phenomenal phase transition (β sheet to α helix) by increase in alcohol concentration from 10% to 70%. Further increase in alcohol concentration (90%) resulted in residual secondary structure in Ntf2 protein. Presence of ammonium sulfate also stabilizes the secondary structure of Ntf2 protein. The structural characterization reveals the flexibility and the stability of Ntf2 at various conditions. These structural alterations in Ntf2 protein probably occurs in the course of nucleocytoplasmic transport when it interacts with other proteins moving towards its final destination.
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Affiliation(s)
- Mohd Kashif
- Center for Plant Molecular Biology Division, CSIR-NBRI, Lucknow, India.
| | | | | | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Abrar Ahmad
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
| | - Bhupendra Kumar
- Center for Plant Molecular Biology Division, CSIR-NBRI, Lucknow, India
| | - Mazin A Zamzami
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Varish Ahmad
- Department of Health and Information Technology, Faculty of Applied Studies, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Sunita Kumari
- ICAR-Indian Institute of Seed Science, Mau, Uttar Pradesh 275103, India
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14
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Dhiman S, Srivastava B, Singh G, Khatri M, Arya SK. Immobilization of mannanase on sodium alginate-grafted-β-cyclodextrin: An easy and cost effective approach for the improvement of enzyme properties. Int J Biol Macromol 2020; 156:1347-1358. [DOI: 10.1016/j.ijbiomac.2019.11.175] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 01/10/2023]
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15
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Samykannu G, Vijayababu P, Antonyraj CB, Narayanan S. Structural investigation of APRs to improve the solubility of outer membrane protease (PgtE) from Salmonella enterica serotype typhi- A multi-constraint approach. Biochem Biophys Rep 2020; 21:100693. [PMID: 31872081 PMCID: PMC6911951 DOI: 10.1016/j.bbrep.2019.100693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 09/03/2019] [Accepted: 10/02/2019] [Indexed: 11/14/2022] Open
Abstract
Outer membrane proteins were playing a crucial role on the several functions controlled by cell membranes even though they are not naturally expressed at higher levels. In order to obtain biologically active protein, the denaturation of these inclusion bodies must be optimized using chaotropic agents. Hence, this study focuses on improving the yield of Outer Membrane Protease (PgtE) from Salmonella enterica serotype Typhi (S. Typhi) using chaotropes and additives. Denaturation methods were tried with various pH, detergents, and reducing agents were used to optimize the solubility of PgtE with biologically active form. Due to the aggregation, we failed to achieve the maximum yield of PgtE. Consequently, we predicted 9 Aggregation Prone Regions (APRs) in PgtE, which are mutated by known structural Gatekeepers. We calculated the Aggregation Index (AI) of PgtE with 10 mM of aspartic acid as an additive in optimized buffer. In addition, the mutations at specific positions within the protein structure can act as APRs suppressors without affecting protein stability with CABS flex dynamics. The multiple sequence analysis demonstrate that aspartic acid is appropriate denaturing additive for other Gram-negative pathogens of Omptin family.
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Affiliation(s)
- Gopinath Samykannu
- Structural Biology Laboratory, Department of Bioinformatics, Bharathiar University, Coimbatore, 641046, Tamil Nadu, India
| | - Princy Vijayababu
- Structural Biology Laboratory, Department of Bioinformatics, Bharathiar University, Coimbatore, 641046, Tamil Nadu, India
| | | | - Sundarabaalaji Narayanan
- Structural Biology Laboratory, Department of Bioinformatics, Bharathiar University, Coimbatore, 641046, Tamil Nadu, India
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16
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Nady D, Zaki A, Raslan M, Hozayen W. Enhancement of microbial lipase activity via immobilization over sodium titanate nanotubes for fatty acid methyl esters production. Int J Biol Macromol 2020; 146:1169-1179. [DOI: 10.1016/j.ijbiomac.2019.09.240] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/18/2019] [Accepted: 09/20/2019] [Indexed: 11/24/2022]
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17
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Lipase immobilization on synthesized hyaluronic acid-coated magnetic nanoparticle-functionalized graphene oxide composites as new biocatalysts: Improved reusability, stability, and activity. Int J Biol Macromol 2020; 145:456-465. [DOI: 10.1016/j.ijbiomac.2019.12.233] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 12/23/2019] [Accepted: 12/25/2019] [Indexed: 01/28/2023]
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18
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Li Y, Zhang H. A novel, kinetically stable copper, zinc superoxide dismutase from Psychropotes longicauda. Int J Biol Macromol 2019; 140:998-1005. [DOI: 10.1016/j.ijbiomac.2019.08.089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 08/08/2019] [Accepted: 08/10/2019] [Indexed: 02/02/2023]
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19
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Spectral elucidation with molecular docking study between isatin analogous and bovine serum albumin. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.cdc.2019.100254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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20
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Zia MK, Siddiqui T, Ali SS, Ahsan H, Khan FH. Deciphering the binding of dutasteride with human alpha-2-macroglobulin: Molecular docking and calorimetric approach. Int J Biol Macromol 2019; 133:1081-1089. [DOI: 10.1016/j.ijbiomac.2019.04.180] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 10/26/2022]
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21
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Dolashki A, Velkova L, Voelter W, Dolashka P. Structural and conformational stability of hemocyanin from the garden snail Cornu aspersum. ACTA ACUST UNITED AC 2019; 74:113-123. [DOI: 10.1515/znc-2018-0084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 02/02/2019] [Indexed: 11/15/2022]
Abstract
Abstract
Various aspects of biomedical applications of molluscan hemocyanins, associated with their immunogenic properties and antitumor activity, promoted us to perform structural studies on these glycoproteins. The stability and reassociation behavior of native Cornu aspersum hemocyanin (CaH) are studied in the presence of different concentrations of Ca2+ and Mg2+ ions and pH values using electron microscopy. Higher concentrations of those ions led to a more rapid reassociation of CaH, resulting in stable multidecamers with different lengths. The conformational changes of native CaH are investigated within a wide pH-temperature range by UV circular dichroism. The relatively small changes of initial [θ]λ indicated that many secondary structural elements are preserved, even at high temperatures above 80°C, especially at neutral pH. The mechanism of thermal unfolding of CaH has a complicated character, and the process is irreversible. The conformational stability of the native didecameric aggregates of CaH toward various denaturants indicates that hydrophilic and polar forces stabilize the quaternary structure. For the first time, the unfolding of native CaH in water solutions in the presence of four different denaturants is investigated. The free energy of stabilization in water, ∆GD
H2O, was calculated in the range of 15.48–16.95 kJ mol−1. The presented results will facilitate the further investigation of the properties and potential applications of CaH.
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Affiliation(s)
- Aleksandar Dolashki
- Institute of Organic Chemistry with Centre of Phytochemistry , Bulgarian Academy of Sciences , Acad. G. Bonchev str., bl.9 , Sofia 1113 , Bulgaria
| | - Lyudmila Velkova
- Institute of Organic Chemistry with Centre of Phytochemistry , Bulgarian Academy of Sciences , Acad. G. Bonchev str., bl.9 , Sofia 1113 , Bulgaria
| | - Wolfgang Voelter
- Interfacultary Institute of Biochemistry , University of Tübingen , Hoppe-Seyler-Straße 4 , D-72076 Tübingen , Germany
| | - Pavlina Dolashka
- Institute of Organic Chemistry with Centre of Phytochemistry , Bulgarian Academy of Sciences , Acad. G. Bonchev str., bl.9 , Sofia 1113 , Bulgaria
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Impact of heat treatments and some technological processing on immunoglobulins of Egyptian buffalo's milk. Int J Biol Macromol 2019; 123:939-944. [DOI: 10.1016/j.ijbiomac.2018.11.055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 11/05/2018] [Accepted: 11/11/2018] [Indexed: 11/21/2022]
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A complete multispectroscopic resolution on the fate of HSA upon interplay with three different glycosaminoglycans inspired silver nanoparticles and straightforward judgment of nanoparticles for recruitment as potent anticancer and antibacterial agent. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.10.090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Chaari A, Fahy C, Chevillot-Biraud A, Rholam M. Insights into Kinetics of Agitation-Induced Aggregation of Hen Lysozyme under Heat and Acidic Conditions from Various Spectroscopic Methods. PLoS One 2015; 10:e0142095. [PMID: 26571264 PMCID: PMC4646502 DOI: 10.1371/journal.pone.0142095] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/16/2015] [Indexed: 01/28/2023] Open
Abstract
Protein misfolding and amyloid formation are an underlying pathological hallmark in a number of prevalent diseases of protein aggregation ranging from Alzheimer’s and Parkinson’s diseases to systemic lysozyme amyloidosis. In this context, we have used complementary spectroscopic methods to undertake a systematic study of the self-assembly of hen egg-white lysozyme under agitation during a prolonged heating in acidic pH. The kinetics of lysozyme aggregation, monitored by Thioflavin T fluorescence, dynamic light scattering and the quenching of tryptophan fluorescence by acrylamide, is described by a sigmoid curve typical of a nucleation-dependent polymerization process. Nevertheless, we observe significant differences between the values deduced for the kinetic parameters (lag time and aggregation rate). The fibrillation process of lysozyme, as assessed by the attenuated total reflection-Fourier transform infrared spectroscopy, is accompanied by an increase in the β-sheet conformation at the expense of the α-helical conformation but the time-dependent variation of the content of these secondary structures does not evolve as a gradual transition. Moreover, the tryptophan fluorescence-monitored kinetics of lysozyme aggregation is described by three phases in which the temporal decrease of the tryptophan fluorescence quantum yield is of quasilinear nature. Finally, the generated lysozyme fibrils exhibit a typical amyloid morphology with various lengths (observed by atomic force microscopy) and contain exclusively the full-length protein (analyzed by highly performance liquid chromatography). Compared to the data obtained by other groups for the formation of lysozyme fibrils in acidic pH without agitation, this work provides new insights into the structural changes (local, secondary, oligomeric/fibrillar structures) undergone by the lysozyme during the agitation-induced formation of fibrils.
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Affiliation(s)
- Ali Chaari
- ITODYS, UMR CNRS 7086, Univ. Paris Diderot, Sorbonne Paris Cité, 75205, Paris, France
- Laboratoire de Génétique et Biologie Cellulaire, Université de Versailles Saint-Quentin-en-Yvelines, 78035, Versailles, France
| | - Christine Fahy
- ITODYS, UMR CNRS 7086, Univ. Paris Diderot, Sorbonne Paris Cité, 75205, Paris, France
| | | | - Mohamed Rholam
- ITODYS, UMR CNRS 7086, Univ. Paris Diderot, Sorbonne Paris Cité, 75205, Paris, France
- * E-mail:
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da Costa G, Ribeiro-Silva C, Ribeiro R, Gilberto S, Gomes RA, Ferreira A, Mateus É, Barroso E, Coelho AV, Freire AP, Cordeiro C. Transthyretin Amyloidosis: Chaperone Concentration Changes and Increased Proteolysis in the Pathway to Disease. PLoS One 2015; 10:e0125392. [PMID: 26147092 PMCID: PMC4492746 DOI: 10.1371/journal.pone.0125392] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 03/24/2015] [Indexed: 11/18/2022] Open
Abstract
Transthyretin amyloidosis is a conformational pathology characterized by the extracellular formation of amyloid deposits and the progressive impairment of the peripheral nervous system. Point mutations in this tetrameric plasma protein decrease its stability and are linked to disease onset and progression. Since non-mutated transthyretin also forms amyloid in systemic senile amyloidosis and some mutation bearers are asymptomatic throughout their lives, non-genetic factors must also be involved in transthyretin amyloidosis. We discovered, using a differential proteomics approach, that extracellular chaperones such as fibrinogen, clusterin, haptoglobin, alpha-1-anti-trypsin and 2-macroglobulin are overrepresented in transthyretin amyloidosis. Our data shows that a complex network of extracellular chaperones are over represented in human plasma and we speculate that they act synergistically to cope with amyloid prone proteins. Proteostasis may thus be as important as point mutations in transthyretin amyloidosis.
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Affiliation(s)
- Gonçalo da Costa
- Centro de Química e Bioquímica, FCUL, Campo Grande, Lisboa, Portugal
| | | | - Raquel Ribeiro
- Centro de Química e Bioquímica, FCUL, Campo Grande, Lisboa, Portugal
| | - Samuel Gilberto
- Centro de Química e Bioquímica, FCUL, Campo Grande, Lisboa, Portugal
| | - Ricardo A Gomes
- Instituto de Tecnologia Química e Biológica, Av. da República Estação Agronómica Nacional, Oeiras, Portugal
| | - António Ferreira
- Centro de Química e Bioquímica, FCUL, Campo Grande, Lisboa, Portugal
| | - Élia Mateus
- Unidade de Transplantação, Hospital Curry Cabral, Lisboa, Portugal
| | - Eduardo Barroso
- Unidade de Transplantação, Hospital Curry Cabral, Lisboa, Portugal
| | - Ana V Coelho
- Instituto de Tecnologia Química e Biológica, Av. da República Estação Agronómica Nacional, Oeiras, Portugal
| | - Ana Ponces Freire
- Centro de Química e Bioquímica, FCUL, Campo Grande, Lisboa, Portugal
| | - Carlos Cordeiro
- Centro de Química e Bioquímica, FCUL, Campo Grande, Lisboa, Portugal
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Inoue A, Tamagawa H, Oaki Y, Aoshima S, Imai H. Switchable dispersivity and molecular-trapping performance of mesostructured CaCO3–thermosensitive polymer composite microspheres. J Mater Chem B 2015; 3:3604-3608. [DOI: 10.1039/c5tb00342c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dispersivity and molecular-trapping performance of mesostructured CaCO3–thermosensitive polymer composite microspheres were switched by a swing in temperature.
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Affiliation(s)
- Atsuharu Inoue
- Department of Applied Chemistry
- Faculty of Science and Technology
- Keio University
- Yokohama 223-8522
- Japan
| | - Hitoshi Tamagawa
- Department of Applied Chemistry
- Faculty of Science and Technology
- Keio University
- Yokohama 223-8522
- Japan
| | - Yuya Oaki
- Department of Applied Chemistry
- Faculty of Science and Technology
- Keio University
- Yokohama 223-8522
- Japan
| | - Sadahito Aoshima
- Department of Macromolecular Science
- Graduate School of Science
- Osaka University
- Osaka 560-0043
- Japan
| | - Hiroaki Imai
- Department of Applied Chemistry
- Faculty of Science and Technology
- Keio University
- Yokohama 223-8522
- Japan
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Rabbani G, Ahmad E, Khan MV, Ashraf MT, Bhat R, Khan RH. Impact of structural stability of cold adapted Candida antarctica lipase B (CaLB): in relation to pH, chemical and thermal denaturation. RSC Adv 2015. [DOI: 10.1039/c4ra17093h] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The effect of pH on the conformational behavior of Candida antartica lipase B (CaLB) has been monitored by spectroscopic and calorimetric studies.
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Affiliation(s)
- Gulam Rabbani
- Interdisciplinary Biotechnology Unit
- Aligarh Muslim University
- Aligarh-202 002
- India
| | - Ejaz Ahmad
- Central European Institute of Technology (CEITEC), Masaryk University
- CZ-62500 Brno
- Czech Republic
| | - Mohsin Vahid Khan
- Interdisciplinary Biotechnology Unit
- Aligarh Muslim University
- Aligarh-202 002
- India
| | | | - Rajiv Bhat
- School of Biotechnology
- Jawaharlal Nehru University
- New-Delhi 110067
- India
| | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit
- Aligarh Muslim University
- Aligarh-202 002
- India
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Wu JW, Chen ME, Wen WS, Chen WA, Li CT, Chang CK, Lo CH, Liu HS, Wang SSS. Comparative analysis of human γD-crystallin aggregation under physiological and low pH conditions. PLoS One 2014; 9:e112309. [PMID: 25389780 PMCID: PMC4229192 DOI: 10.1371/journal.pone.0112309] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 10/04/2014] [Indexed: 11/19/2022] Open
Abstract
Cataract, a major cause of visual impairment worldwide, is the opacification of the eye’s crystalline lens due to aggregation of the crystallin proteins. The research reported here is aimed at investigating the aggregating behavior of γ-crystallin proteins in various incubation conditions. Thioflavin T binding assay, circular dichroism spectroscopy, 1-anilinonaphthalene-8-sulfonic acid fluorescence spectroscopy, intrinsic (tryptophan) fluorescence spectroscopy, light scattering, and electron microscopy were used for structural characterization. Molecular dynamics simulations and bioinformatics prediction were performed to gain insights into the γD-crystallin mechanisms of fibrillogenesis. We first demonstrated that, except at pH 7.0 and 37°C, the aggregation of γD-crystallin was observed to be augmented upon incubation, as revealed by turbidity measurements. Next, the types of aggregates (fibrillar or non-fibrillar aggregates) formed under different incubation conditions were identified. We found that, while a variety of non-fibrillar, granular species were detected in the sample incubated under pH 7.0, the fibrillogenesis of human γD-crystallin could be induced by acidic pH (pH 2.0). In addition, circular dichroism spectroscopy, 1-anilinonaphthalene-8-sulfonic acid fluorescence spectroscopy, and intrinsic fluorescence spectroscopy were used to characterize the structural and conformational features in different incubation conditions. Our results suggested that incubation under acidic condition led to a considerable change in the secondary structure and an enhancement in solvent-exposure of the hydrophobic regions of human γD-crystallin. Finally, molecular dynamics simulations and bioinformatics prediction were performed to better explain the differences between the structures and/or conformations of the human γD-crystallin samples and to reveal potential key protein region involved in the varied aggregation behavior. Bioinformatics analyses revealed that the initiation of amyloid formation of human γD-crystallin may be associated with a region within the C-terminal domain. We believe the results from this research may contribute to a better understanding of the possible mechanisms underlying the pathogenesis of senile nuclear cataract.
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Affiliation(s)
- Josephine W. Wu
- Department of Optometry, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan
- * E-mail: (JWW); (SSW)
| | - Mei-Er Chen
- Department of Entomology, National Chung Hsing University, Taichung 402, Taiwan
| | - Wen-Sing Wen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Wei-An Chen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Chien-Ting Li
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Chih-Kai Chang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Chun-Hsien Lo
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Hwai-Shen Liu
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Steven S.-S. Wang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
- * E-mail: (JWW); (SSW)
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Saini K, Khan MAI, Chakrapani S, Deep S. Transforming growth factor receptor type II (ec-TβR II) behaves as a halophile. Int J Biol Macromol 2014; 72:1104-10. [PMID: 25316422 DOI: 10.1016/j.ijbiomac.2014.09.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 09/25/2014] [Accepted: 09/27/2014] [Indexed: 11/17/2022]
Abstract
The members of transforming growth factor β family (TGF-β) are multifunctional proteins but their main role is to control cell proliferation and differentiation. Polypeptides of TGF-β family function by binding to two related, functionally distinct transmembrane receptor kinases, first to the type II (TβR II) followed by type I receptor (TβR I). The paper describes, in details, the stability of wt-ec-TβR II under different conditions. The stability of wt-ec-TβR II was observed at different pH and salt concentration using fluorescence spectroscopy. Stability of ec-TβR II decreases with decrease in pH. Interestingly, the addition of salt increases the stability of the TβRII at pH 5.0 as observed for halophiles. Computational analysis using DELPHI suggests that this is probably due to the decrease in repulsion between negatively charged residues at surface on the addition of salt. This is further confirmed by the change in the stability of receptor on mutation of some of the residues (D32A) at surface.
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A structural study on the protection of glycation of superoxide dismutase by thymoquinone. Int J Biol Macromol 2014; 69:476-81. [PMID: 24933520 DOI: 10.1016/j.ijbiomac.2014.06.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/01/2014] [Accepted: 06/07/2014] [Indexed: 01/21/2023]
Abstract
Accumulation of advanced glycation end products (AGEs) in tissues and serum plays important roles in diabetes-associated complications. Therefore, the identification of antiglycating compounds is attracting considerable interest. In this study, the structural changes associated with the glycation of superoxide dismutase (SOD) and its protection by thymoquinone (TQ) have been investigated by biophysical techniques. Incubation of SOD with glucose, methylglyoxal (MG) or both at 37̊C resulted in progressive hyperchromicity at 280nm, intrinsic fluorescence quenching at 310nm, decrease in negative ellipticity at 208nm, AGE-specific fluorescence enhancement in the wavelength range 400-480nm and Thioflavin T (ThT) fluorescence enhancement at 480nm (fibrillar state enhancement). Therefore, glycation by glucose or MG induced both tertiary and secondary structural changes in SOD and formation of AGEs and fibrils. The changes were more and faster with MG than with glucose since MG is a stronger glycating agent than glucose. TQ offered protection against glucose or MG-induced glycation of SOD as observed by a reduction in the structural changes, formation of AGEs and fibrils. Thus, TQ can be used for reducing diabetic complications many of which are due to protein glycation.
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Cosolvents Induced Unfolding and Aggregation of Keyhole Limpet Hemocyanin. Cell Biochem Biophys 2013; 69:103-13. [DOI: 10.1007/s12013-013-9776-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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32
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Rabbani G, Kaur J, Ahmad E, Khan RH, Jain SK. Structural characteristics of thermostable immunogenic outer membrane protein from Salmonella enterica serovar Typhi. Appl Microbiol Biotechnol 2013; 98:2533-43. [PMID: 23949993 PMCID: PMC7080034 DOI: 10.1007/s00253-013-5123-3] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/14/2013] [Accepted: 07/10/2013] [Indexed: 02/08/2023]
Abstract
In this work, we explored the acid-induced unfolding pathway of non-porin outer membrane protein (OMP), an immunogenic protein from Salmonella Typhi, by monitoring the conformational changes over a pH range of 1.0-7.0 by circular dichroism, intrinsic fluorescence, ANS binding, acrylamide quenching, and dynamic light scattering. The spectroscopic measurements showed that OMP in its native state at pH 7.0 exists in more stable and compact conformation. In contrast, at pH 2.0, OMP retains substantial amount of secondary structure, disrupted side chain interactions, increased hydrodynamic radii, and nearly four-fold increase in ANS fluorescence with respect to the native state, indicating that MG state exists at pH 2.0. Quenching of tryptophan fluorescence by acrylamide further confirmed the accumulation of a partially unfolded state between native and unfolded state. The effect of pH on the conformation and thermostability of OMP points towards its heat resistance at neutral pH (T m ~ 69 °C at pH 7.0, monitored by change in MRE222 nm). Acid unfolded state was also characterized by the lack of a cooperative thermal transition. All these results suggested that acid-induced unfolded state of OMP at pH 2.0 represented the molten globule state. The chemical denaturation studies with GuHCl and urea as denaturants showed dissimilar results. The chemical unfolding experiments showed that in both far-UV CD and fluorescence measurements, GuHCl is more efficient than urea. GuHCl is characterized by low C m (~1 M), while urea is characterized by high C m (~3 M). The fully unfolded states were reached at 2 M GuHCl and 4 M urea concentration, respectively. This study adds to several key considerations of importance in the development of therapeutic agents against typhoid fever for clinical purposes.
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Affiliation(s)
- Gulam Rabbani
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002, India
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Yadav JK. A differential behavior of α-amylase, in terms of catalytic activity and thermal stability, in response to higher concentration CaCl2. Int J Biol Macromol 2012; 51:146-52. [PMID: 22542853 DOI: 10.1016/j.ijbiomac.2012.04.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 04/08/2012] [Accepted: 04/12/2012] [Indexed: 11/28/2022]
Abstract
A differential relationship was observed between thermal stability and catalytic activity of α-amylase in the presence of different concentrations of CaCl(2). The enzyme displays optimum catalytic activity in the presence of 1.0-2.0 mM CaCl(2). Further addition of CaCl(2) leads to inhibition of the enzyme, however, at the same time the enzyme gains an additional resistance against thermal denaturation. It was evident that the enzyme is thermodynamically more stable (compared to the active enzyme) in the presence of inhibitory concentration of CaCl(2). For example, the thermal transition temperature (T(m)) of optimally active α-amylase was found to be 64±1°C, whereas, for the less active enzyme (in the presence 10 mM CaCl(2)) the value was determined to be 71±1°C. Similarly, the activation energy of thermal inactivation (Ea) was found to be 228±12 kJ/mol and 291±15 kJ/mol for the optimally active enzyme and the enzyme in the presence of 10 mM CaCl(2), respectively. Biophysical analysis of different states of the enzymes in response to variable calcium level indicates no significant change in the secondary structure in response to different concentration of CaCl(2), however the less active but thermodynamically stable enzyme (in the presence of higher concentration of CaCl(2)) was shown to have relatively more compact structure. The results suggest that the enzyme has separate catalytic and structure stabilizing domains and they significantly vary in their functional attributes in response to calcium level.
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Affiliation(s)
- Jay Kant Yadav
- Department of Protein Chemistry and Technology, Central Food Technological Research Institute, Mysore, India.
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pH-Induced Molten Globule State of Rhizopus niveus Lipase is More Resistant Against Thermal and Chemical Denaturation Than Its Native State. Cell Biochem Biophys 2012; 62:487-99. [DOI: 10.1007/s12013-011-9335-9] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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pH-Dependent Conformational Transitions in Conalbumin (Ovotransferrin), a Metalloproteinase from Hen Egg White. Cell Biochem Biophys 2011; 61:551-60. [DOI: 10.1007/s12013-011-9237-x] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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