1
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Song Y, Wang Z, Ji H, Jiang Z, Li X, Du Z, Wei S, Sun Y. Fatty acid modification of casein bioactive peptides nano-assemblies, synthesis, characterization and anticarcinogenic effect. Int J Biol Macromol 2024; 254:127718. [PMID: 37918594 DOI: 10.1016/j.ijbiomac.2023.127718] [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: 09/04/2023] [Revised: 10/24/2023] [Accepted: 10/25/2023] [Indexed: 11/04/2023]
Abstract
In this study, the nano-assemblies of bovine casein hydrolyzed peptides (HP) modified by fatty acids with various alkyl chain lengths (C8, C10, C12 and C14) were synthesized. The physicochemical properties of HP-C8-HP-C14 nano-assemblies were characterized using spectra, laser particle size analyzer, contact angle meter, scanning electron microscope (SEM) and cryo-transmission electron microscope (Cryo-TEM). HP-C8 and HP-C10 self-assembled into a hollow cube cage with an average size of ~500 nm, and the assembly of HP-C12 showed a flower-shaped morphology with more dispersed behavior, and droplet size was observed as ~20 nm. The in vitro cytotoxicity against human breast cancer cells MCF-7 was tested using CCK-8 assay and flow cytometry analysis. HP-C12 showed the highest cytotoxicity for MCF-7 cells with an inhibition rate of 66.03 % ± 0.35 % with an IC50 value of 7.4 μM among HP-Cn. HP-C8, HP-C10 and HP-C12 significantly affected on the migration, invasion and apoptosis of MCF-7 cells. The apoptosis mechanism may depend on the upregulation of anti-apoptotic protein Bcl-2 as well as pro-apoptotic proteins Bax and caspase-8. The dead MCF-7 cells were analyzed with UHPLC-MS/MS using untargeted metabolomics, revealing key metabolic pathways.
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Affiliation(s)
- Yang Song
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Zhichun Wang
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Hang Ji
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Zhongyou Jiang
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Xiujuan Li
- Pharmaceutical Department, The Affiliated Taian City Central Hospital of Qingdao University, Taian, 271000, China
| | - Zhongyao Du
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Song Wei
- Tumor Precise Intervention and Translational Medicine Laboratory, The Affiliated Taian City Central Hospital of Qingdao University, Taian, 271000, China.
| | - Yang Sun
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China.
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2
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Warrender AK, Pan J, Pudney C, Arcus VL, Kelton W. Red edge excitation shift spectroscopy is highly sensitive to tryptophan composition. J R Soc Interface 2023; 20:20230337. [PMID: 37935360 PMCID: PMC10645072 DOI: 10.1098/rsif.2023.0337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 10/16/2023] [Indexed: 11/09/2023] Open
Abstract
Red edge excitation shift (REES) spectroscopy relies on the unique emission profiles of fluorophore-solvent interactions to profile protein molecular dynamics. Recently, we reported the use of REES to compare the stability of 32 polymorphic IgG antibodies natively containing tryptophan reporter fluorophores. Here, we expand on this work to investigate the sensitivity of REES to variations in tryptophan content using a subset of IgG3 antibodies containing arginine to tryptophan polymorphisms. Structural analysis revealed that the additional tryptophan residues were situated in highly solvated environments. Subsequently, REES showed clear differences in fluorescence emission profiles when compared with the unmutated variants, thereby limiting direct comparison of their structural dynamics. These findings highlight the exquisite sensitivity of REES to minor variations in protein structure and tryptophan composition.
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Affiliation(s)
| | - Jolyn Pan
- Te Aka Mātuatua School of Science, University of Waikato, Hamilton, New Zealand
| | - Chris Pudney
- Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - Vickery L. Arcus
- Te Aka Mātuatua School of Science, University of Waikato, Hamilton, New Zealand
| | - William Kelton
- Te Huataki Waiora School of Health, University of Waikato, Hamilton, New Zealand
- Te Aka Mātuatua School of Science, University of Waikato, Hamilton, New Zealand
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3
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Martínez-Rosas V, Hernández-Ochoa B, Morales-Luna L, Ortega-Cuellar D, González-Valdez A, Arreguin-Espinosa R, Rufino-González Y, Calderón-Jaimes E, Castillo-Rodríguez RA, Wong-Baeza C, Baeza-Ramírez I, Pérez de la Cruz V, Vidal-Limón A, Gómez-Manzo S. Nitazoxanide Inhibits the Bifunctional Enzyme GlG6PD::6PGL of Giardia lamblia: Biochemical and In Silico Characterization of a New Druggable Target. Int J Mol Sci 2023; 24:11516. [PMID: 37511272 PMCID: PMC10380810 DOI: 10.3390/ijms241411516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/08/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
Giardiasis, which is caused by Giardia lamblia infection, is a relevant cause of morbidity and mortality worldwide. Because no vaccines are currently available to treat giardiasis, chemotherapeutic drugs are the main options for controlling infection. Evidence has shown that the nitro drug nitazoxanide (NTZ) is a commonly prescribed treatment for giardiasis; however, the mechanisms underlying NTZ's antigiardial activity are not well-understood. Herein, we identified the glucose-6-phosphate::6-phosphogluconate dehydrogenase (GlG6PD::6PGL) fused enzyme as a nitazoxanide target, as NTZ behaves as a GlG6PD::6PGL catalytic inhibitor. Furthermore, fluorescence assays suggest alterations in the stability of GlG6PD::6PGL protein, whereas the results indicate a loss of catalytic activity due to conformational and folding changes. Molecular docking and dynamic simulation studies suggest a model of NTZ binding on the active site of the G6PD domain and near the structural NADP+ binding site. The findings of this study provide a novel mechanistic basis and strategy for the antigiardial activity of the NTZ drug.
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Affiliation(s)
- Víctor Martínez-Rosas
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City 04530, Mexico
- Programa de Posgrado en Biomedicina y Biotecnología Molecular, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Beatriz Hernández-Ochoa
- Laboratorio de Inmunoquímica, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Mexico City 06720, Mexico
| | - Laura Morales-Luna
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City 04530, Mexico
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Daniel Ortega-Cuellar
- Laboratorio de Nutrición Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City 04530, Mexico
| | - Abigail González-Valdez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Roberto Arreguin-Espinosa
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Yadira Rufino-González
- Laboratorio de Parasitología Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City 04530, Mexico
| | - Ernesto Calderón-Jaimes
- Laboratorio de Inmunoquímica, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Mexico City 06720, Mexico
| | | | - Carlos Wong-Baeza
- Laboratorio de Biomembranas, Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Isabel Baeza-Ramírez
- Laboratorio de Biomembranas, Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Verónica Pérez de la Cruz
- Neurobiochemistry and Behavior Laboratory, National Institute of Neurology and Neurosurgery "Manuel Velasco Suárez", Mexico City 14269, Mexico
| | - Abraham Vidal-Limón
- Red de Estudios Moleculares Avanzados, Clúster Científico y Tecnológico BioMimic®, Instituto de Ecología A.C. (INECOL), Carretera Antigua a Coatepec 351, El Haya, Xalapa 91073, Mexico
| | - Saúl Gómez-Manzo
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City 04530, Mexico
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4
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Pal S, Bose D, Chakrabarti A, Chattopadhyay A. Comparative Analysis of Tryptophan Dynamics in Spectrin and Its Constituent Domains: Insights from Fluorescence. J Phys Chem B 2021; 126:1045-1053. [PMID: 34845910 DOI: 10.1021/acs.jpcb.1c08600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spectrin is a cytoskeletal protein ubiquitous in metazoan cells that acts as a liaison between the plasma membrane and the cellular interior and imparts mechanical stability to the plasma membrane. Spectrin is known to be highly dynamic, with an appreciable degree of torsional and segmental mobility. In this context, we have earlier utilized the red edge excitation shift (REES) approach to report the retention of restricted solvation dynamics and local structure in the vicinity of spectrin tryptophans on urea denaturation and loss of spectrin secondary structure. As a natural progression of our earlier work, in this work, we carried out a biophysical dissection of tryptophan solvation and rotational dynamics in spectrin and its constituent domains, in order to trace the origin of local structure retention observed in denatured spectrin. Our results show that the ankyrin binding domain (and, to a lesser extent, the β-tetramerization domain) is capable of retention of local structure, similar to that observed for intact spectrin. However, all α-chain domains studied exhibit negligible retention of local structure on urea denaturation. Such a stark chain-specific retention of local structure could originate from the fact that the β-chain domains possess specialized functions, where conservation of local (structural) integrity may be a prerequisite for optimum cellular function. To the best of our knowledge, these observations represent one of the first systematic biophysical dissections of spectrin dynamics in terms of its constituent domains and add to emerging literature on comprehensive domain-based analysis of spectrin organization, dynamics, and function.
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Affiliation(s)
- Sreetama Pal
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Dipayan Bose
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India.,Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
| | - Abhijit Chakrabarti
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India.,Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
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5
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Goswami S, Manna B, Chattopadhyay K, Ghosh A, Datta S. Role of Conformational Change and Glucose Binding Sites in the Enhanced Glucose Tolerance of Agrobacterium tumefaciens 5A GH1 β-Glucosidase Mutants. J Phys Chem B 2021; 125:9402-9416. [PMID: 34384214 DOI: 10.1021/acs.jpcb.1c02150] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
β-Glucosidases are often inhibited by their reaction product glucose and a barrier to the efficient lignocellulosic biomass hydrolysis to glucose. We had previously reported the mutants, C174V, and H229S, with a nearly 2-fold increased glucose tolerance over the wild type (WT), H0HC94, encoded in Agrobacterium tumefaciens 5A (apparent Ki,Glc = 686 mM). We report our steady-state and time-resolved intrinsic fluorescence spectroscopy, circular dichroism, and isothermal titration calorimetry (ITC) studies to further understand increased glucose tolerance. Changes in the mutants' emission intensity and the differential change in quenching rate in the absence and presence of glucose reflect changes in protein conformation by glucose. Time-resolved lifetime and anisotropy measurements further indicated the microenvironment differences across solvent-exposed tryptophan residues and a higher hydrodynamic radius due to glucose binding, respectively. ITC measurements confirmed the increase of glucose binding sites in the mutants. The experiment results were supported by molecular dynamics simulations, which revealed significant variations in the glucose-protein hydrogen-bonding profiles. Protein structure network analysis of the simulated structures further indicates the mutants' conformation change than the WT. Computational studies also indicated additional glucose binding sites in mutants. Our results indicate the role of glucose binding in modulating the enzyme response to glucose.
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Affiliation(s)
- Shubhasish Goswami
- Protein Engineering Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Bharat Manna
- School of Energy Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Krishnananda Chattopadhyay
- Structural Biology & Bio-Informatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mallick Road, Kolkata 700032, India
| | - Amit Ghosh
- School of Energy Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India.,P. K. Sinha Centre for Bioenergy and Renewables, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Supratim Datta
- Protein Engineering Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India.,Center for the Advanced Functional Materials, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India.,Center for the Climate and Environmental Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
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6
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Monoclonal antibody stability can be usefully monitored using the excitation-energy-dependent fluorescence edge-shift. Biochem J 2021; 477:3599-3612. [PMID: 32869839 PMCID: PMC7527260 DOI: 10.1042/bcj20200580] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/27/2020] [Accepted: 09/01/2020] [Indexed: 11/17/2022]
Abstract
Among the major challenges in the development of biopharmaceuticals are structural heterogeneity and aggregation. The development of a successful therapeutic monoclonal antibody (mAb) requires both a highly active and also stable molecule. Whilst a range of experimental (biophysical) approaches exist to track changes in stability of proteins, routine prediction of stability remains challenging. The fluorescence red edge excitation shift (REES) phenomenon is sensitive to a range of changes in protein structure. Based on recent work, we have found that quantifying the REES effect is extremely sensitive to changes in protein conformational state and dynamics. Given the extreme sensitivity, potentially this tool could provide a ‘fingerprint’ of the structure and stability of a protein. Such a tool would be useful in the discovery and development of biopharamceuticals and so we have explored our hypothesis with a panel of therapeutic mAbs. We demonstrate that the quantified REES data show remarkable sensitivity, being able to discern between structurally identical antibodies and showing sensitivity to unfolding and aggregation. The approach works across a broad concentration range (µg–mg/ml) and is highly consistent. We show that the approach can be applied alongside traditional characterisation testing within the context of a forced degradation study (FDS). Most importantly, we demonstrate the approach is able to predict the stability of mAbs both in the short (hours), medium (days) and long-term (months). The quantified REES data will find immediate use in the biopharmaceutical industry in quality assurance, formulation and development. The approach benefits from low technical complexity, is rapid and uses instrumentation which exists in most biochemistry laboratories without modification.
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7
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Novel insights in linking solvent relaxation dynamics and protein conformations utilizing red edge excitation shift approach. Emerg Top Life Sci 2021; 5:89-101. [PMID: 33416893 DOI: 10.1042/etls20200256] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/14/2020] [Accepted: 12/18/2020] [Indexed: 01/01/2023]
Abstract
Protein hydration dynamics plays an important role in many physiological processes since protein fluctuations, slow solvation, and the dynamics of hydrating water are all intrinsically related. Red edge excitation shift (REES) is a unique and powerful wavelength-selective (i.e. excitation-energy dependent) fluorescence approach that can be used to directly monitor the environment-induced restriction and dynamics around a polar fluorophore in a complex biological system. This review is mainly focused on recent applications of REES and a novel analysis of REES data to monitor the structural dynamics, functionally relevant conformational transitions and to unmask the structural ensembles in proteins. In addition, the novel utility of REES in imaging protein aggregates in a cellular context is discussed. We believe that the enormous potential of REES approach showcased in this review will engage more researchers, particularly from life sciences.
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8
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Lo SY, Goulet DL, Fraaz U, Siemann S. Effect of pH and denaturants on the fold and metal status of anthrax lethal factor. Arch Biochem Biophys 2020; 692:108547. [PMID: 32828796 DOI: 10.1016/j.abb.2020.108547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 08/02/2020] [Accepted: 08/17/2020] [Indexed: 01/26/2023]
Abstract
Anthrax lethal factor (LF) is a critical component of the anthrax toxin, and functions intracellularly as a zinc-dependent endopeptidase targeting proteins involved in maintaining critical host signaling pathways. To reach the cytoplasm, LF requires to be unfolded and guided through the narrow protective antigen pore in a pH-dependent process. The current study sought to address the question as to whether LF is capable of retaining its metal ion when exposed to a low-pH environment (similar to that found in late endosomes) and an unfolding stress (induced by urea). Using a combination of tryptophan fluorescence spectroscopy and chelation studies, we show that a decrease in the pH value (from 7.0 to 5.0) leads to a pronounced shift in the onset of structural alterations in LF to lower urea concentrations. More importantly, the enzyme was found to retain its Zn2+ ion beyond the unfolding transitions monitored by Trp fluorescence, a finding indicative of tight metal binding to LF in a non-native state. In addition, an analysis of red-edge excitation shift (REES) spectra suggests the protein to maintain residual structure (a feature necessary for metal binding) even at very high denaturant concentrations. Furthermore, studies using the chromophoric chelator 4-(2-pyridylazo)resorcinol (PAR) revealed LF's Zn2+ ion to become accessible to complexation at urea concentrations in between those required to cause structural changes and metal dissociation. This phenomenon likely originates from the conversion of a PAR-inaccessible (closed) to a PAR-accessible (open) state of LF at intermediate denaturant concentrations.
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Affiliation(s)
- Suet Y Lo
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
| | - Danica L Goulet
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
| | - Usama Fraaz
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
| | - Stefan Siemann
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada.
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Mora-Gutierrez A, Attaie R, Núñez de González MT, Jung Y, Marquez SA. Interface Compositions as Determinants of Resveratrol Stability in Nanoemulsion Delivery Systems. Foods 2020; 9:foods9101394. [PMID: 33023075 PMCID: PMC7601424 DOI: 10.3390/foods9101394] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 09/25/2020] [Accepted: 09/30/2020] [Indexed: 01/07/2023] Open
Abstract
The incorporation of hydrophobic ingredients, such as resveratrol (a fat-soluble phytochemical), in nanoemulsions can increase the water solubility and stability of these hydrophobic ingredients. The nanodelivery of resveratrol can result in a marked improvement in the bioavailability of this health-promoting ingredient. The current study hypothesized that resveratrol can bind to caprine casein, which may result in the preservation of the biological properties of resveratrol. The fluorescence spectra provided proof of this complex formation by demonstrating that resveratrol binds to caprine casein in the vicinity of tryptophan amino acid residues. The caprine casein/resveratrol complex is stabilized by hydrophobic interactions and hydrogen bonds. Hence, to study the rate of resveratrol degradation during processing/storage, resveratrol losses were determined by reversed-phase high performance liquid chromatography (RP-HPLC) in nanoemulsions stabilized by bovine and caprine caseins individually and in combination with polysorbate-20. At 48 h oxidation, 88.33% and 89.08% was left of resveratrol in the nanoemulsions stabilized by caprine casein (αs1-I)/polysorbate-20 complex and caprine (αs1-II)/polysorbate-20 complex, while there was less resveratrol left in the nanoemulsions stabilized by bovine casein/polysorbate-20 complex, suggesting that oxygen degradation was involved. The findings of this study are crucial for the food industry since they imply the potential use of caprine casein/polysorbate-20 complex to preserve the biological properties of resveratrol.
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Affiliation(s)
- Adela Mora-Gutierrez
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446, USA; (R.A.); (M.T.N.d.G.); (Y.J.)
- Correspondence: ; Fax: +1-936-261-9975
| | - Rahmat Attaie
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446, USA; (R.A.); (M.T.N.d.G.); (Y.J.)
| | - Maryuri T. Núñez de González
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446, USA; (R.A.); (M.T.N.d.G.); (Y.J.)
| | - Yoonsung Jung
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446, USA; (R.A.); (M.T.N.d.G.); (Y.J.)
| | - Sixto A. Marquez
- Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843, USA;
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10
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Cao F, Xia Y, Chen D, Xu N, Hemar Y, Li N, Sun Y. Insights on the structure of caseinate particles based on surfactants-induced dissociation. Food Hydrocoll 2020. [DOI: 10.1016/j.foodhyd.2020.105766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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11
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Structural and conformational behavior of MurE ligase from Salmonella enterica serovar Typhi at different temperature and pH conditions. Int J Biol Macromol 2020; 150:389-399. [DOI: 10.1016/j.ijbiomac.2020.01.306] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/30/2020] [Accepted: 01/31/2020] [Indexed: 11/20/2022]
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12
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Hu X, Zhang X, Chen D, Li N, Hemar Y, Yu B, Tang S, Sun Y. How much can we trust polysorbates as food protein stabilizers - The case of bovine casein. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.05.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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13
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Gulácsy CE, Meade R, Catici DAM, Soeller C, Pantos GD, Jones DD, Alibhai D, Jepson M, Valev VK, Mason JM, Williams RJ, Pudney CR. Excitation-Energy-Dependent Molecular Beacon Detects Early Stage Neurotoxic Aβ Aggregates in the Presence of Cortical Neurons. ACS Chem Neurosci 2019; 10:1240-1250. [PMID: 30346718 DOI: 10.1021/acschemneuro.8b00322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
There is now crucial medical importance placed on understanding the role of early stage, subvisible protein aggregation, particularly in neurodegenerative disease. While there are strategies for detecting such aggregates in vitro, there is no approach at present that can detect these toxic species associated with cells and specific subcellular compartments. We have exploited excitation-energy-dependent fluorescence edge-shift of recombinant protein labeled with a molecular beacon, to provide a sensitive read out for the presence of subvisible protein aggregates. To demonstrate the potential utility of the approach, we examine the major peptide associated with the initiation of Alzheimer's disease, amyloid β-protein (Aβ) at a patho-physiologically relevant concentration in mouse cortical neurons. Using our approach, we find preliminary evidence that subvisible Aβ aggregates are detected at specific subcellular regions and that neurons drive the formation of specific Aβ aggregate conformations. These findings therefore demonstrate the potential of a novel fluorescence-based approach for detecting and imaging protein aggregates in a cellular context, which can be used to sensitively probe the association of early stage toxic protein aggregates within subcellular compartments.
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Affiliation(s)
| | | | | | - Christian Soeller
- Biomedical Physics, University of Exeter, Exeter EX4 4QD, United Kingdom
| | | | - D. Dafydd Jones
- School of Biosciences, Cardiff University, Cardiff CF10 3TL, United Kingdom
| | - Dominic Alibhai
- Wolfson Bioimaging Facility, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Mark Jepson
- Wolfson Bioimaging Facility, University of Bristol, Bristol BS8 1TS, United Kingdom
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14
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Constrained dynamics of the sole tryptophan in the third intracellular loop of the serotonin 1A receptor. Biophys Chem 2018; 240:34-41. [PMID: 29885563 DOI: 10.1016/j.bpc.2018.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 05/24/2018] [Accepted: 05/27/2018] [Indexed: 12/19/2022]
Abstract
G protein-coupled receptors (GPCRs) are major signaling proteins in eukaryotic cells and are important drug targets. In spite of their role in GPCR function, the extramembranous regions of GPCRs are relatively less appreciated. The third intracellular loop (ICL3), which connects transmembrane helices V and VI, is important in this context since its crucial role in signaling has been documented for a number of GPCRs. Unfortunately, the structure of this loop is generally not visualized in x-ray crystallographic studies since this flexible loop is either stabilized using a monoclonal antibody or replaced with lysozyme. In this work, we expressed and purified the ICL3 region of the serotonin1A receptor and monitored its motional restriction and organization utilizing red edge excitation shift (REES) of its sole tryptophan and circular dichroism (CD) spectroscopy. Our results show that the tryptophan in ICL3 exhibits REES of 4 nm, implying that it is localized in a restricted microenvironment. These results are further supported by wavelength-selective changes in fluorescence anisotropy and lifetime. This constrained dynamics was relaxed upon denaturation of the peptide, thereby suggesting the involvement of the peptide secondary structure in the observed motional restriction, as evident from CD spectroscopy and apparent rotational correlation time. To the best of our knowledge, these results constitute one of the first measurements of motional constraint in the ICL3 region of GPCRs. Our results are relevant in the context of the reported intrinsically disordered nature of ICL3 and its role in providing functional diversity to GPCRs due to conformational plasticity.
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15
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Nielsen LR, Lund MN, Davies MJ, Nielsen JH, Nielsen SB. Effect of free cysteine on the denaturation and aggregation of holo α-lactalbumin. Int Dairy J 2018. [DOI: 10.1016/j.idairyj.2017.11.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Mora-Gutierrez A, Attaie R, Núñez de González MT, Jung Y, Woldesenbet S, Marquez SA. Complexes of lutein with bovine and caprine caseins and their impact on lutein chemical stability in emulsion systems: Effect of arabinogalactan. J Dairy Sci 2017; 101:18-27. [PMID: 29103708 DOI: 10.3168/jds.2017-13105] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 09/06/2017] [Indexed: 11/19/2022]
Abstract
Lutein is an important xanthophyll carotenoid with many benefits to human health. Factors affecting the application of lutein as a functional ingredient in low-fat dairy-like beverages (pH 6.0-7.0) are not well understood. The interactions of bovine and caprine caseins with hydrophobic lutein were studied using UV/visible spectroscopy as well as fluorescence. Our studies confirmed that the aqueous solubility of lutein is improved after binding with bovine and caprine caseins. The rates of lutein solubilization by the binding to bovine and caprine caseins were as follows: caprine αS1-II-casein 34%, caprine αS1-I-casein 10%, and bovine casein 7% at 100 μM lutein. Fluorescence of the protein was quenched on binding supporting complex formation. The fluorescence experiments showed that the binding involves tryptophan residues and some nonspecific interactions. Scatchard plots of lutein binding to the caseins demonstrated competitive binding between the caseins and their sites of interaction with lutein. Competition experiments suggest that caprine αS1-II casein will bind a larger number of lutein molecules with higher affinity than other caseins. The chemical stability of lutein was largely dependent on casein type and significant increases occurred in the chemical stability of lutein with the following pattern: caprine αS1-II-casein > caprine αS1-I-casein > bovine casein. Addition of arabinogalactan to lutein-enriched emulsions increases the chemical stability of lutein-casein complexes during storage under accelerated photo-oxidation conditions at 25°C. Therefore, caprine αS1-II-casein alone and in combination with arabinogalactan can have important applications in the beverage industry as carrier of this xanthophyll carotenoid (lutein).
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Affiliation(s)
- A Mora-Gutierrez
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446.
| | - R Attaie
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446
| | - M T Núñez de González
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446
| | - Y Jung
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446
| | - S Woldesenbet
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446
| | - S A Marquez
- Cooperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX 77446
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17
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Sensing Tryptophan Microenvironment of Amyloid Protein Utilizing Wavelength-Selective Fluorescence Approach. J Fluoresc 2017; 27:1995-2000. [DOI: 10.1007/s10895-017-2138-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 06/30/2017] [Indexed: 12/11/2022]
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18
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Ursache MF, Dumitraşcu L, Aprodu I, Stănciuc N. Screening the thermal stability of carotenoids-α lactalbumin complex by spectroscopic and molecular modeling approach. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2017. [DOI: 10.1080/10601325.2017.1294456] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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19
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α-Lactalbumin and sodium dodecyl sulfate aggregates: Denaturation, complex formation and time stability. Food Hydrocoll 2017. [DOI: 10.1016/j.foodhyd.2016.07.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Chaudhuri A, Prasanna X, Agiru P, Chakraborty H, Rydström A, Ho JCS, Svanborg C, Sengupta D, Chattopadhyay A. Protein-dependent Membrane Interaction of A Partially Disordered Protein Complex with Oleic Acid: Implications for Cancer Lipidomics. Sci Rep 2016; 6:35015. [PMID: 27731329 PMCID: PMC5059734 DOI: 10.1038/srep35015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/09/2016] [Indexed: 12/18/2022] Open
Abstract
Bovine α-lactalbumin (BLA) forms cytotoxic complexes with oleic acid (OA) that perturbs tumor cell membranes, but molecular determinants of these membrane-interactions remain poorly understood. Here, we aim to obtain molecular insights into the interaction of BLA/BLA-OA complex with model membranes. We characterized the folding state of BLA-OA complex using tryptophan fluorescence and resolved residue-specific interactions of BLA with OA using molecular dynamics simulation. We integrated membrane-binding data using a voltage-sensitive probe and molecular dynamics (MD) to demonstrate the preferential interaction of the BLA-OA complex with negatively charged membranes. We identified amino acid residues of BLA and BLA-OA complex as determinants of these membrane interactions using MD, functionally corroborated by uptake of the corresponding α-LA peptides across tumor cell membranes. The results suggest that the α-LA component of these cytotoxic complexes confers specificity for tumor cell membranes through protein interactions that are maintained even in the lipid complex, in the presence of OA.
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Affiliation(s)
- Arunima Chaudhuri
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | | | - Priyanka Agiru
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Anna Rydström
- Department of Microbiology, Immunology and Glycobiology (MIG), Institute of Laboratory Medicine, Lund University, Lund, Sweden
| | - James C. S. Ho
- Centre for Biomimetic Sensor Science, School of Materials Science & Engineering, Nanyang Technological University, 637553 Singapore
| | - Catharina Svanborg
- Department of Microbiology, Immunology and Glycobiology (MIG), Institute of Laboratory Medicine, Lund University, Lund, Sweden
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21
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Catici DAM, Amos HE, Yang Y, van den Elsen JMH, Pudney CR. The red edge excitation shift phenomenon can be used to unmask protein structural ensembles: implications for NEMO-ubiquitin interactions. FEBS J 2016; 283:2272-84. [PMID: 27028374 DOI: 10.1111/febs.13724] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 03/29/2016] [Indexed: 02/02/2023]
Abstract
To understand complex molecular interactions, it is necessary to account for molecular flexibility and the available equilibrium of conformational states. Only a small number of experimental approaches can access such information. Potentially steady-state red edge excitation shift (REES) spectroscopy can act as a qualitative metric of changes to the protein free energy landscape (FEL) and the equilibrium of conformational states. First, we validate this hypothesis using a single Trp-containing protein, NF-κB essential modulator (NEMO). We provide detailed evidence from chemical denaturation studies, macromolecular crowding studies, and the first report of the pressure dependence of the REES effect. Combination of these data demonstrate that the REES effect can report on the 'ruggedness' of the FEL and we present a phenomenological model, based on realistic physical interpretations, for fitting steady-state REES data to allow quantification of this aspect of the REES effect. We test the conceptual framework we have developed by correlating findings from NEMO ligand-binding studies with the REES data in a range of NEMO-ligand binary complexes. Our findings shed light on the nature of the interaction between NEMO and poly-ubiquitin, suggesting that NEMO is differentially regulated by poly-ubiquitin chain length and that this regulation occurs via a modulation of the available equilibrium of conformational states, rather than gross structural change. This study therefore demonstrates the potential of REES as a powerful tool for tackling contemporary issues in structural biology and biophysics and elucidates novel information on the structure-function relationship of NEMO and key interaction partners.
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Affiliation(s)
- Dragana A M Catici
- Department of Biology and Biochemistry, Faculty of Science, University of Bath, UK
| | - Hope E Amos
- Department of Biology and Biochemistry, Faculty of Science, University of Bath, UK
| | - Yi Yang
- Department of Biology and Biochemistry, Faculty of Science, University of Bath, UK
| | | | - Christopher R Pudney
- Department of Biology and Biochemistry, Faculty of Science, University of Bath, UK
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22
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Yi J, Fan Y, Yokoyama W, Zhang Y, Zhao L. Characterization of milk proteins–lutein complexes and the impact on lutein chemical stability. Food Chem 2016; 200:91-7. [DOI: 10.1016/j.foodchem.2016.01.035] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 01/08/2016] [Accepted: 01/09/2016] [Indexed: 01/24/2023]
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23
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Narang D, Singh A, Mukhopadhyay S. Stepwise unfolding of human β2-microglobulin into a disordered amyloidogenic precursor at low pH. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 46:65-76. [DOI: 10.1007/s00249-016-1138-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 04/20/2016] [Accepted: 05/10/2016] [Indexed: 02/08/2023]
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24
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Sun Y, Filho PLO, Bozelli JC, Carvalho J, Schreier S, Oliveira CLP. Unfolding and folding pathway of lysozyme induced by sodium dodecyl sulfate. SOFT MATTER 2015; 11:7769-7777. [PMID: 26308474 DOI: 10.1039/c5sm01231g] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Proteins may exhibit an unfolding or folding state in the presence of a surfactant. In the present study, the unfolding and folding pathway of hen egg white lysozyme (HEWL) induced by sodium dodecyl sulfate (SDS) is studied. The stoichiometry obtained from isothermal titration calorimetry (ITC) provides guidelines for other techniques. The fluorescence spectra and circular dichroism show that the fluorescence properties and secondary structure of proteins undergo a two-step change upon binding with SDS, in which the intensity decreases, the emission blue shifts and the helical conformation decreases at low ratios of SDS to HEWL, while all of them return to the native-like state upon the addition of SDS at higher ratios. At the end of the binding, HEWL presents a higher α-helical content but its tertiary structure is lost compared to its native state, which is namely a molten globule state. Small angle X-ray scattering (SAXS) analysis and the derived model reveal that the complexes possess a decorated core-shell structure, with the core composed of dodecyl chains and the shell consisting of SDS head groups with a protein in molten globule state. Five binding steps, including the individual details involved in the denaturation, were obtained to describe the unfolding and folding pathway of HEWL induced by SDS. The results of this study not only present details about the denaturation of protein induced by SDS and the structure of the complexes involved in each binding step, but also provide molecular insights into the mechanism of the higher helical conformation of proteins in the presence of surfactant micelles.
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Affiliation(s)
- Yang Sun
- Instituto de Física, Universidade de São Paulo, Rua do Matão 187, São Paulo-SP, 05314-970, Brasil.
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25
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Mitra M, Chaudhuri A, Patra M, Mukhopadhyay C, Chakrabarti A, Chattopadhyay A. Organization and Dynamics of Tryptophan Residues in Brain Spectrin: Novel Insight into Conformational Flexibility. J Fluoresc 2015; 25:707-17. [DOI: 10.1007/s10895-015-1556-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 03/05/2015] [Indexed: 10/23/2022]
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26
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Chaudhuri A, Chattopadhyay A. Lipid binding specificity of bovine α-lactalbumin: A multidimensional approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2078-86. [DOI: 10.1016/j.bbamem.2014.04.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 04/27/2014] [Accepted: 04/28/2014] [Indexed: 10/25/2022]
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27
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Chattopadhyay A, Haldar S. Dynamic insight into protein structure utilizing red edge excitation shift. Acc Chem Res 2014; 47:12-9. [PMID: 23981188 DOI: 10.1021/ar400006z] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Proteins are considered the workhorses in the cellular machinery. They are often organized in a highly ordered conformation in the crowded cellular environment. These conformations display characteristic dynamics over a range of time scales. An emerging consensus is that protein function is critically dependent on its dynamics. The subtle interplay between structure and dynamics is a hallmark of protein organization and is essential for its function. Depending on the environmental context, proteins can adopt a range of conformations such as native, molten globule, unfolded (denatured), and misfolded states. Although protein crystallography is a well established technique, it is not always possible to characterize various protein conformations by X-ray crystallography due to transient nature of these states. Even in cases where structural characterization is possible, the information obtained lacks dynamic component, which is needed to understand protein function. In this overall scenario, approaches that reveal information on protein dynamics are much appreciated. Dynamics of confined water has interesting implications in protein folding. Interfacial hydration combines the motion of water molecules with the slow moving protein molecules. The red edge excitation shift (REES) approach becomes relevant in this context. REES is defined as the shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of absorption spectrum. REES arises due to slow rates (relative to fluorescence lifetime) of solvent relaxation (reorientation) around an excited state fluorophore in organized assemblies such as proteins. Consequently, REES depends on the environment-induced motional restriction imposed on the solvent molecules in the immediate vicinity of the fluorophore. In the case of a protein, the confined water in the protein creates a dipolar field that acts as the solvent for a fluorophore in the protein. In this Account, we focus on REES to monitor organization and dynamics of soluble and membrane proteins utilizing intrinsic protein fluorescence. We discuss here the application of REES in various conformations of proteins. While application of REES to proteins in native conformation has been in use for a long time, our work highlights the potential of this approach in case of molten globule and denatured conformations. For example, we have demonstrated the presence of residual structure, that could not be detected using other methods, by REES of denatured spectrin. Given the functional relevance of such residual structures, these results are very far reaching. We discuss here the application of REES to molten globule conformation and to the green fluorescent protein (GFP). The case of GFP is particularly interesting since the dipolar field in this case is provided by the protein matrix itself and not confined water. We envision that future applications of REES in proteins will involve generating a dynamic hydration map of the protein, which would allow us to explore protein function in terms of local dynamics and hydration.
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Affiliation(s)
- Amitabha Chattopadhyay
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007 India
| | - Sourav Haldar
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007 India
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28
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In vitro hyperglycemic condition facilitated the aggregation of lysozyme via the passage through a molten globule state. Cell Biochem Biophys 2013. [PMID: 23184703 DOI: 10.1007/s12013-012-9479-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Hyperglycemic condition i.e. an increase in blood glucose concentration has been linked to bring about structural alterations in the native state of proteins. Glucose concentrations of 50 and 100 mM in vitro, which correspond to hyperglycemic condition, were tested to investigate their effect on lysozyme native structure. Incubating enzyme with 50 and 100 mM glucose for a period of 7 days, an intermediate state on day 4 and 3 was observed, respectively. The presence of intermediate state was characterized by a 22 % increase in the intrinsic fluorescence intensity with a red shift of 20 nm compared to the native state, a 5 % increase in ANS-fluorescence intensity relative to the native due to the surfacing of hydrophobic clusters and a sharp decrease in near-UV CD signal at around 284 and 291 nm. The state retains substantial native-like secondary structure. This partially unfolded intermediate state can be referred as 'molten globule', which finally tends to aggregate on day 6 and 4 with 50 and 100 mM glucose concentration, respectively, as a result of cross-linking between lysozyme molecules. The aggregates were confirmed by the presence of β-sheet structure as depicted by far-UV CD, an increase in ThT fluorescence as well as the fibrillar morphology shown by SEM. Moreover, advanced glycation end products were also accompanied as the emission peak was observed at 460 and 470 nm corresponding to the formation of pentosidine and malonaldehyde, respectively.
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29
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Chakraborti S, Sarwar S, Chakrabarti P. The Effect of the Binding of ZnO Nanoparticle on the Structure and Stability of α-Lactalbumin: A Comparative Study. J Phys Chem B 2013; 117:13397-408. [DOI: 10.1021/jp404411b] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
| | - Shamila Sarwar
- Department of Biochemistry, Bose Institute, Kolkata 700054, India
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30
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Khan JM, Qadeer A, Ahmad E, Ashraf R, Bhushan B, Chaturvedi SK, Rabbani G, Khan RH. Monomeric banana lectin at acidic pH overrules conformational stability of its native dimeric form. PLoS One 2013; 8:e62428. [PMID: 23638080 PMCID: PMC3637162 DOI: 10.1371/journal.pone.0062428] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 03/21/2013] [Indexed: 11/18/2022] Open
Abstract
Banana lectin (BL) is a homodimeric protein categorized among jacalin-related family of lectins. The effect of acidic pH was examined on conformational stability of BL by using circular dichroism, intrinsic fluorescence, 1-anilino-8-napthalene sulfonate (ANS) binding, size exclusion chromatography (SEC) and dynamic light scattering (DLS). During acid denaturation of BL, the monomerization of native dimeric protein was found at pH 2.0. The elution profile from SEC showed two different peaks (59.65 ml & 87.98 ml) at pH 2.0 while single peak (61.45 ml) at pH 7.4. The hydrodynamic radii (R h) of native BL was 2.9 nm while at pH 2.0 two species were found with R h of 1.7 and 3.7 nm. Furthermore at, pH 2.0 the secondary structures of BL remained unaltered while tertiary structure was significantly disrupted with the exposure of hydrophobic clusters confirming the existence of molten globule like state. The unfolding of BL with different subunit status was further evaluated by urea and temperature mediated denaturation to check their stability. As inferred from high Cm and ΔG values, the monomeric form of BL offers more resistance towards chemical denaturation than the native dimeric form. Besides, dimeric BL exhibited a Tm of 77°C while no loss in secondary structures was observed in monomers even up to 95°C. To the best of our knowledge, this is the first report on monomeric subunit of lectins showing more stability against denaturants than its native dimeric state.
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Affiliation(s)
- Javed M. Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Atiyatul Qadeer
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Ejaz Ahmad
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Raghib Ashraf
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Bharat Bhushan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Sumit K. Chaturvedi
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Gulam Rabbani
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Rizwan H. Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
- * E-mail:
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31
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Thakkar SV, Kim JH, Samra HS, Sathish HA, Bishop SM, Joshi SB, Volkin DB, Middaugh CR. Local Dynamics and Their Alteration by Excipients Modulate the Global Conformational Stability of an lgG1 Monoclonal Antibody. J Pharm Sci 2012; 101:4444-57. [DOI: 10.1002/jps.23332] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 08/18/2012] [Accepted: 09/11/2012] [Indexed: 12/11/2022]
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32
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Correlation of TrpGly and GlyTrp Rotamer Structure with W7 and W10 UV Resonance Raman Modes and Fluorescence Emission Shifts. JOURNAL OF AMINO ACIDS 2012; 2012:735076. [PMID: 22888404 PMCID: PMC3408653 DOI: 10.1155/2012/735076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 05/04/2012] [Indexed: 11/18/2022]
Abstract
Tryptophyl glycine (TrpGly) and glycyl tryptophan (GlyTrp) dipeptides at pH 5.5 and pH 9.3 show a pattern of fluorescence emission shifts with the TrpGly zwitterion emission solely blue shifted. This pattern is matched by shifts in the UV resonance Raman (UVRR) W10 band position and the W7 Fermi doublet band ratio. Ab initio calculations show that the 1340 cm−1 band of the W7 doublet is composed of three modes, two of which determine the W7 band ratios for the dipeptides. Molecular dynamics simulations show that the dipeptides take on two conformations: one with the peptide backbone extended; one with the backbone curled over the indole. The dihedral angle critical to these conformations is χ1 and takes on three discrete values. Only the TrpGly zwitterion spends an appreciable amount of time in the extended backbone conformation as this is stabilized by two hydrogen bonds with the terminal amine cation. According to a Stark effect model, a positive charge near the pyrrole keeps the 1La transition at high energy, limiting fluorescence emission red shift, as observed for the TrpGly zwitterion. The hydrogen bond stabilized backbone provides a rationale for the Cmethylene-Cα-Ccarbonyl W10 symmetric stretch that is unique to the TrpGly zwitterion.
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33
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Zhang Y, Zhong Q. Effects of thermal denaturation on binding between bixin and whey protein. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:7526-7531. [PMID: 22784187 DOI: 10.1021/jf3021656] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Heating is commonly used in the manufacture of dairy products, but impacts of thermal denaturation on binding between whey protein and molecules such as pigments are poorly understood. The objective of this work was to study the impacts of thermal denaturation on binding between bixin, a pigment relevant to colored cheeses, and whey proteins using several complementary techniques. Fluorescence spectroscopy data showed that heat treatment caused tryptophan in β-lactoglobulin and α-lactalbumin to be exposed to a more polar environment, but the opposite was observed for bovine serum albumin. The fluorescence quenching study indicated that the quenching of whey protein fluorescence by bixin was static quenching, and the affinity of binding with bixin was enhanced after thermal denaturation, caused by a higher extent of unordered structures, as revealed by results from circular dichroism and Fourier transform infrared spectra. β-Lactoglobulin was responsible for overall impacts of thermal denaturation on binding between bixin and whey protein isolate.
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Affiliation(s)
- Yue Zhang
- Department of Food Science and Technology, University of Tennessee , Knoxville, Tennessee 37996, United States
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34
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Halder UC, Chakraborty J, Das N, Bose S. Tryptophan dynamics in the exploration of micro-conformational changes of refolded β-lactoglobulin after thermal exposure: A steady state and time-resolved fluorescence approach. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2012; 109:50-7. [DOI: 10.1016/j.jphotobiol.2012.01.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 12/28/2011] [Accepted: 01/24/2012] [Indexed: 11/28/2022]
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35
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Zhang Y, Zhong Q. Binding between bixin and whey protein at pH 7.4 studied by spectroscopy and isothermal titration calorimetry. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:1880-1886. [PMID: 22268806 DOI: 10.1021/jf2050262] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Bixin is the major coloring component of annatto used in manufacturing colored cheeses, but its presence in liquid whey causes undesirable quality of the recovered whey protein ingredients. The objective of this work was to study molecular binding between bixin and three major whey proteins (β-lactoglobulin, α-lactalbumin, and bovine serum albumin) at pH 7.4 using UV-vis absorption spectroscopy, fluorescence spectroscopy, isothermal titration calorimetry, and circular dichroism. These complementary techniques illustrated that the binding is a spontaneous complexation process mainly driven by hydrophobic interactions. The complexation is favored at a lower temperature and a higher ionic strength. At a lower temperature, the binding is entropy-driven, while it changes to an enthalpy-driven process at higher temperatures. The binding also increases the percentage of unordered secondary structures of proteins. Findings from this work can be used to develop whey protein recovery processes for minimizing residual annatto content in whey protein ingredients.
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Affiliation(s)
- Yue Zhang
- Department of Food Science and Technology, University of Tennessee, Knoxville, Tennessee 37996, USA
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36
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Bhattacharya M, Mukhopadhyay S. Structural and Dynamical Insights into the Molten-Globule Form of Ovalbumin. J Phys Chem B 2011; 116:520-31. [DOI: 10.1021/jp208416d] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mily Bhattacharya
- Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, India
| | - Samrat Mukhopadhyay
- Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, India
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37
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Applications of pressure perturbation calorimetry in biophysical studies. Biophys Chem 2011; 156:13-23. [DOI: 10.1016/j.bpc.2010.12.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 12/29/2010] [Accepted: 12/29/2010] [Indexed: 10/18/2022]
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