1
|
Sawyer TK, Aral E, Staros JV, Bobst CE, Garman SC. Human Saposin B Ligand Binding and Presentation to α-Galactosidase A. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.04.584535. [PMID: 38617236 PMCID: PMC11014568 DOI: 10.1101/2024.04.04.584535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Sphingolipid activator protein B (saposin B; SapB) is an essential activator of globotriaosylceramide (Gb3) catabolism by α-galactosidase A. However, the manner by which SapB stimulates α-galactosidase A activity remains unknown. To uncover the molecular mechanism of SapB presenting Gb3 to α-galactosidase A, we subjected the fluorescent substrate globotriaosylceramide-nitrobenzoxidazole (Gb3-NBD) to a series of biochemical and structural assays involving SapB. First, we showed that SapB stably binds Gb3-NBD using a fluorescence equilibrium binding assay, isolates Gb3-NBD from micelles, and facilitates α-galactosidase A cleavage of Gb3-NBD in vitro. Second, we crystallized SapB in the presence of Gb3-NBD and validated the ligand-bound assembly. Third, we captured transient interactions between SapB and α-galactosidase A by chemical cross-linking. Finally, we determined the crystal structure of SapB bound to α-galactosidase A. These findings establish general principles for molecular recognition in saposin:hydrolase complexes and highlight the utility of NBD reporter lipids in saposin biochemistry and structural biology.
Collapse
Affiliation(s)
- Thomas K Sawyer
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Efecan Aral
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - James V Staros
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Cedric E Bobst
- Mass Spectrometry Core Facility, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Scott C Garman
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| |
Collapse
|
2
|
Das A, Bysack A, Raghuraman H. Cholesterol modulates the structural dynamics of the paddle motif loop of KvAP voltage sensor. Curr Res Struct Biol 2024; 7:100137. [PMID: 38500801 PMCID: PMC10945132 DOI: 10.1016/j.crstbi.2024.100137] [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: 11/29/2023] [Revised: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 03/20/2024] Open
Abstract
KvAP is a prokaryotic Kv channel, which has been widely used as a model system to understand voltage- and lipid-dependent gating mechanisms. In phospholipid membranes, the KvAP-VSD adopts the activated/'Up' conformation, whereas the presence of non-phospholipids in membranes favours the structural transition to resting/'Down' state. The S3b-S4 paddle motif loop of KvAP-VSD is functionally important as this participates in protein-protein interactions and is the target for animal toxins. In this study, we have monitored the modulatory role of cholesterol - the physiologically-relevant non-phospholipid - on the organization and dynamics of the S3b-S4 loop of the isolated KvAP-VSD in membranes by site-directed fluorescence approaches using the environmental sensitivity of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-ethylenediamine (NBD) fluorescence. Our results show that cholesterol alters the dynamic nature (rotational and hydration dynamics) of S3b-S4 loop in a segmental fashion, i.e., the residues 110 to 114 and 115 to 117 behave differently in the presence of cholesterol, which is accompanied by considerable change in conformational heterogeneity. Further, quantitative depth measurements using the parallax quenching method reveal that the sensor loop is located at the shallow interfacial region of cholesterol-containing membranes, suggesting that the sensor loop organization is not directly correlated with S4 helix movement. Our results clearly show that cholesterol-induced changes in bilayer properties may not be the predominant factor for the sensor loop's altered structural dynamics, but can be attributed to the conformational change of the KvAP-VSD in cholesterol-containing membranes. Overall, these results are relevant for gating mechanisms, particularly the lipid-dependent gating, of Kv channels in membranes.
Collapse
Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - Arpan Bysack
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| |
Collapse
|
3
|
Site-directed fluorescence approaches to monitor the structural dynamics of proteins using intrinsic Trp and labeled with extrinsic fluorophores. STAR Protoc 2022; 3:101200. [PMID: 35252885 PMCID: PMC8889417 DOI: 10.1016/j.xpro.2022.101200] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Comprehensive understanding of a protein’s function depends on having reliable, sophisticated tools to study protein structural dynamics in physiologically-relevant conditions. Here, we present an effective, robust step-by-step protocol to monitor the structural dynamics (including hydration dynamics) of a protein utilizing various site-directed fluorescence (SDFL) approaches. This protocol should be widely applicable for studying soluble proteins, intrinsically-disordered proteins, and membrane proteins. For complete details on the use and execution of this protocol, please refer to Das et al. (2020), Das and Raghuraman (2021), and Chatterjee et al. (2021). A step-by-step protocol to monitor the structural dynamics of proteins using SDFL Applicable to proteins with intrinsic Trp and labeled with extrinsic fluorophores This protocol should be widely applicable for soluble and membrane proteins
Collapse
|
4
|
Environment-Sensitive Fluorescence of 7-Nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-Labeled Ligands for Serotonin Receptors. Molecules 2021; 26:molecules26133848. [PMID: 34202630 PMCID: PMC8270269 DOI: 10.3390/molecules26133848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 12/21/2022] Open
Abstract
Serotonin is a neurotransmitter that plays a crucial role in the regulation of several behavioral and cognitive functions by binding to a number of different serotonin receptors present on the cell surface. We report here the synthesis and characterization of several novel fluorescent analogs of serotonin in which the fluorescent NBD (7-nitrobenz-2-oxa-1,3-diazol-4-yl) group is covalently attached to serotonin. The fluorescent ligands compete with the serotonin1A receptor specific radiolabeled agonist for binding to the receptor. Interestingly, these fluorescent ligands display a high environmental sensitivity of their fluorescence. Importantly, the human serotonin1A receptor stably expressed in CHO-K1 cells could be specifically labeled with one of the fluorescent ligands with minimal nonspecific labeling. Interestingly, we show by spectral imaging that the NBD-labeled ligand exhibits a red edge excitation shift (REES) of 29 nm when bound to the receptor, implying that it is localized in a restricted microenvironment. Taken together, our results show that NBD-labeled serotonin analogs offer an attractive fluorescent approach for elucidating the molecular environment of the serotonin binding site in serotonin receptors. In view of the multiple roles played by the serotonergic systems in the central and peripheral nervous systems, these fluorescent ligands would be useful in future studies involving serotonin receptors.
Collapse
|
5
|
Versatility of Reverse Micelles: From Biomimetic Models to Nano (Bio)Sensor Design. Processes (Basel) 2021. [DOI: 10.3390/pr9020345] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
This paper presents an overview of the principal structural and dynamics characteristics of reverse micelles (RMs) in order to highlight their structural flexibility and versatility, along with the possibility to modulate their parameters in a controlled manner. The multifunctionality in a large range of different scientific fields is exemplified in two distinct directions: a theoretical model for mimicry of the biological microenvironment and practical application in the field of nanotechnology and nano-based sensors. RMs represent a convenient experimental approach that limits the drawbacks of the conventionally biological studies in vitro, while the particular structure confers them the status of simplified mimics of cells by reproducing a complex supramolecular organization in an artificial system. The biological relevance of RMs is discussed in some particular cases referring to confinement and a crowded environment, as well as the molecular dynamics of water and a cell membrane structure. The use of RMs in a range of applications seems to be more promising due to their structural and compositional flexibility, high efficiency, and selectivity. Advances in nanotechnology are based on developing new methods of nanomaterial synthesis and deposition. This review highlights the advantages of using RMs in the synthesis of nanoparticles with specific properties and in nano (bio)sensor design.
Collapse
|
6
|
Chatterjee S, Brahma R, Raghuraman H. Gating-related Structural Dynamics of the MgtE Magnesium Channel in Membrane-Mimetics Utilizing Site-Directed Tryptophan Fluorescence. J Mol Biol 2020; 433:166691. [PMID: 33203509 DOI: 10.1016/j.jmb.2020.10.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/17/2020] [Accepted: 10/19/2020] [Indexed: 12/25/2022]
Abstract
Magnesium is the most abundant divalent cation present in the cell, and an abnormal Mg2+ homeostasis is associated with several diseases in humans. However, among ion channels, the mechanisms of intracellular regulation and transport of Mg2+ are poorly understood. MgtE is a homodimeric Mg2+-selective channel and is negatively regulated by high intracellular Mg2+ concentration where the cytoplasmic domain of MgtE acts as a Mg2+ sensor. Most of the previous biophysical studies on MgtE have been carried out in detergent micelles and the information regarding gating-related structural dynamics of MgtE in physiologically-relevant membrane environment is scarce. In this work, we monitored the changes in gating-related structural dynamics, hydration dynamics and conformational heterogeneity of MgtE in micelles and membranes using the intrinsic site-directed Trp fluorescence. For this purpose, we have engineered six single-Trp mutants in the functional Trp-less background of MgtE to obtain site-specific information on the gating-related structural dynamics of MgtE in membrane-mimetic systems. Our results indicate that Mg2+-induced gating might involve the possibility of a 'conformational wave' from the cytosolic N-domain to transmembrane domain of MgtE. Although MgtE is responsive to Mg2+-induced gating in both micelles and membranes, the organization and dynamics of MgtE is substantially altered in physiologically important phospholipid membranes compared to micelles. This is accompanied by significant changes in hydration dynamics and conformational heterogeneity. Overall, our results highlight the importance of lipid-protein interactions and are relevant for understanding gating mechanism of magnesium channels in general, and MgtE in particular.
Collapse
Affiliation(s)
- Satyaki Chatterjee
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India.
| |
Collapse
|
7
|
Rashid TU, Kabir SMF, Biswas MC, Bhuiyan MAR. Sustainable Wastewater Treatment via Dye–Surfactant Interaction: A Critical Review. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c00676] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Taslim Ur Rashid
- Department of Textile Engineering, Chemistry and Science, Wilson College of Textiles, North Carolina State University, 1020 Main Campus Drive, Raleigh, North Carolina 27695, United States
| | - S M Fijul Kabir
- Department of Textile Engineering, Chemistry and Science, Wilson College of Textiles, North Carolina State University, 1020 Main Campus Drive, Raleigh, North Carolina 27695, United States
| | - Manik Chandra Biswas
- Department of Textile Engineering, Chemistry and Science, Wilson College of Textiles, North Carolina State University, 1020 Main Campus Drive, Raleigh, North Carolina 27695, United States
| | - M. A. Rahman Bhuiyan
- Department of Textile Engineering, Dhaka University of Engineering and Technology, Gazipur 1707, Bangladesh
| |
Collapse
|
8
|
Raghuraman H, Chatterjee S, Das A. Site-Directed Fluorescence Approaches for Dynamic Structural Biology of Membrane Peptides and Proteins. Front Mol Biosci 2019; 6:96. [PMID: 31608290 PMCID: PMC6774292 DOI: 10.3389/fmolb.2019.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins mediate a number of cellular functions and are associated with several diseases and also play a crucial role in pathogenicity. Due to their importance in cellular structure and function, they are important drug targets for ~60% of drugs available in the market. Despite the technological advancement and recent successful outcomes in determining the high-resolution structural snapshot of membrane proteins, the mechanistic details underlining the complex functionalities of membrane proteins is least understood. This is largely due to lack of structural dynamics information pertaining to different functional states of membrane proteins in a membrane environment. Fluorescence spectroscopy is a widely used technique in the analysis of functionally-relevant structure and dynamics of membrane protein. This review is focused on various site-directed fluorescence (SDFL) approaches and their applications to explore structural information, conformational changes, hydration dynamics, and lipid-protein interactions of important classes of membrane proteins that include the pore-forming peptides/proteins, ion channels/transporters and G-protein coupled receptors.
Collapse
Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
| | | | | |
Collapse
|
9
|
Das A, Chatterjee S, Raghuraman H. Structural Dynamics of the Paddle Motif Loop in the Activated Conformation of KvAP Voltage Sensor. Biophys J 2019; 118:873-884. [PMID: 31547975 DOI: 10.1016/j.bpj.2019.08.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/31/2019] [Accepted: 08/06/2019] [Indexed: 02/07/2023] Open
Abstract
Voltage-dependent potassium (Kv) channels play a fundamental role in neuronal and cardiac excitability and are potential therapeutic targets. They assemble as tetramers with a centrally located pore domain surrounded by a voltage-sensing domain (VSD), which is critical for sensing transmembrane potential and subsequent gating. Although the sensor is supposed to be in "Up" conformation in both n-octylglucoside (OG) micelles and phospholipid membranes in the absence of membrane potential, toxins that bind VSD and modulate the gating behavior of Kv channels exhibit dramatic affinity differences in these membrane-mimetic systems. In this study, we have monitored the structural dynamics of the S3b-S4 loop of the paddle motif in activated conformation of KvAP-VSD by site-directed fluorescence approaches, using the environment-sensitive fluorescent probe 7-nitrobenz-2-oxa-1,3-diazol-4-yl-ethylenediamine (NBD). Emission maximum of NBD-labeled loop region of KvAP-VSD (residues 110-117) suggests a significant change in the polarity of local environment in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) membranes compared to OG micelles. This indicates that S3b-S4 loop residues might be partitioning to membrane interface, which is supported by an overall increased mean fluorescence lifetimes and significantly reduced water accessibility in membranes. Further, the magnitude of red edge excitation shift (REES) supports the presence of restricted/bound water molecules in the loop region of the VSD in micelles and membranes. Quantitative analysis of REES data using Gaussian probability distribution function clearly indicates that the sensor loop has fewer discrete equilibrium conformational states when reconstituted in membranes. Interestingly, this reduced molecular heterogeneity is consistent with the site-specific NBD polarization results, which suggest that the membrane environment offers a relaxed/dynamic organization for most of the S3b-S4 loop residues of the sensor. Overall, our results are relevant for understanding toxin-VSD interaction and gating mechanisms of Kv channels in membranes.
Collapse
Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - Satyaki Chatterjee
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India.
| |
Collapse
|
10
|
Reynoso E, Cacciari RD, Suchetti CA, Montejano HA, Biasutti MA. Influence of pH and micellar systems on the sensitized photo-oxidation of bovine serum albumin. LUMINESCENCE 2019; 34:324-333. [PMID: 30740864 DOI: 10.1002/bio.3610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 01/03/2019] [Accepted: 01/07/2019] [Indexed: 12/24/2022]
Abstract
Photosensitized oxidation of bovine serum albumin (BSA), by using perinaphtenone as a sensitizer, has been studied at pH 7.4 and 11. The selected sensitizer does not present ground-state complexation with BSA and ensures that the mechanism is mediated by O2 (1 △g ). Strong dependence between BSA-O2 (1 △g ) photo-oxidation and the pH of the medium has been found. The relative oxygen uptake rate (v- △ O2 ) and the total quenching rate constant (kt ) values are higher at pH 11 than pH 7.4. The enhancement in the alkaline condition is due to conformational changes in the protein and the reactivity of tyrosinate anion with O2 (1 △g ). Even when the tendency with the pH in the presence of sodium dodecyl sulfate (SDS) micelles is similar to that observed in homogeneous media, an increment on the kt value is detected. This effect may be attributable to the strong interaction of BSA-SDS, which leads to the protein unfolding and could leave more exposed photo-oxidizable amino acids. A protective effect against the O2 (1 △g )-mediated photo-oxidation was observed in reverse micelles (RMs) of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) by comparing the kt values obtained at W = 10 with respect to the one obtain in homogeneous media. The latter could be mainly explained by the modification in the solvent polarity. Also, another important observation was found, the internal pH inside RMs of AOT sensed through tyrosine absorption was independent of the one used for the formation of the water pool. Hence, the kt values observed at both pH, are quite similar.
Collapse
Affiliation(s)
- Eugenia Reynoso
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - R Daniel Cacciari
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - Carlos A Suchetti
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - Hernán A Montejano
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - M Alicia Biasutti
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| |
Collapse
|
11
|
Feng L, Chhabra M, So WH, Zhu Q, Xia J, Sun H. A proximity-induced covalent fluorescent probe for selective detection of bromodomain 4. CHINESE CHEM LETT 2018. [DOI: 10.1016/j.cclet.2018.05.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
12
|
Ghosh S, Singharoy D, Bhattacharya SC. Spectroscopic and theoretical investigation of conformational changes of proteins by synthesized pyrimidine derivative and its sensitivity towards FRET application. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 195:7-15. [PMID: 29358093 DOI: 10.1016/j.saa.2018.01.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 12/29/2017] [Accepted: 01/11/2018] [Indexed: 06/07/2023]
Abstract
Interest in synthesizing and characterizing (IR, NMR and HRMS spectroscopic methods) a pyrimidine based Schiff-base ligand, 2-(2-(Anthracen-9-ylmethylene) hydrazinyl)-4,6-dimethyl pyrimidine (ANHP) has been developed for its application to ascertain the conformational change of protein and sensitivity towards fluorescence resonance energy transfer (FRET) process. Location of ANHP in bovine serum albumin (BSA) and human serum albumin (HSA) proteins environment has been determined using different spectroscopic techniques. Weakly fluorescent ANHP have shown greater protein induced fluorescence enhancement (PIFE) in case of HSA than BSA, though in both cases energy transfer efficiency are almost same but difference in binding constant values encourages us to find the location of ANHP within the complex protein environment. From the FRET parameter and α-helicity change, it has been found that ANHP bound with Trp-214 of HSA and surface Trp-134 of BSA. Conformational changes of proteins have been observed more for HSA than BSA in presence of ANHP, which has confirmed the location of ANHP in both the protein environments. Coupled with experimental studies, molecular docking analysis has also been done to explain the locations and distance dependent FRET process of ANHP in both proteins.
Collapse
Affiliation(s)
- Swadesh Ghosh
- Department of Chemistry, Jadavpur University, Kolkata 700032, India
| | - Dipti Singharoy
- Department of Chemistry, Jadavpur University, Kolkata 700032, India
| | | |
Collapse
|
13
|
Odella E, Falcone RD, Ceolín M, Silber JJ, Correa NM. Structural Characterization of Biocompatible Reverse Micelles Using Small-Angle X-ray Scattering, 31P Nuclear Magnetic Resonance, and Fluorescence Spectroscopy. J Phys Chem B 2018; 122:4366-4375. [PMID: 29589933 DOI: 10.1021/acs.jpcb.7b11395] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The most critical problem regarding the use of reverse micelles (RMs) in several fields is the toxicity of their partial components. In this sense, many efforts have been made to characterize nontoxic RM formulations on the basis of biological amphiphiles and/or different oils. In this contribution, the microstructure of biocompatible mixed RMs formulated by sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) and tri- n-octylphosphine oxide (TOPO) surfactants dispersed in the friendly solvent methyl laurate was studied by using SAXS and 31P NMR and by following the solvatochromic behavior of the molecular probe 4-aminophthalimide (4-AP). The results indicated the presence of RM aggregates upon TOPO incorporation with a droplet size reduction and an increase in the interfacial fluidity in comparison with pure AOT RMs. When confined inside the mixed systems, 4-AP showed a red-edge excitation shift and confirmed the increment of interfacial fluidity upon TOPO addition. Also, the partition between the external nonpolar solvent and the RM interface and an increase in both the local micropolarity and the capability to form a hydrogen bond interaction between 4-AP and a mixed interface were observed. The findings have been explained in terms of the nonionic surfactant structure and its complexing nature expressed at the interfacial level. Notably, we show how two different approaches, i.e., SAXS and the solvatochromism of the probe 4-AP, can be used in a complementary way to enhance our understanding of the interfacial fluidity of RMs, a parameter that is difficult to measure directly.
Collapse
Affiliation(s)
- Emmanuel Odella
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| | - R Darío Falcone
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| | - Marcelo Ceolín
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas , UNLP-CONICET (CCT-La Plata) , Diagonal 113 y 64 , C.P. B1906ZAA , La Plata , Argentina
| | - Juana J Silber
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| | - N Mariano Correa
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| |
Collapse
|
14
|
Villa CC, Silber JJ, Falcone RD, Correa NM. Subtleties of catanionic surfactant reverse micelle assemblies revealed by a fluorescent molecular probe. Methods Appl Fluoresc 2017; 5:044001. [PMID: 28653961 DOI: 10.1088/2050-6120/aa7b64] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In this work, the absorption and emission behavior of the cationic hemicyanine trans-4-[4-(dimethylamino)styryl]-N-methylpyridinium iodide (HC) in reverse micelles (RMs) formed by the catanionic surfactants benzyl-n-hexadecyldimethylammonium-1,4-bis-2-ethylhexylsulfosuccinate (AOT-BHD) and cetyltrimethylammonium-1,4-bis-2-ethylhexylsulfosuccinate (AOT-CTA) have been investigated. Our results show that the spectroscopic behavior of HC changes when the dye is dissolved in AOT-BHD or in AOT-CTA RMs. While HC undergoes an intramolecular charge-transfer process upon excitation in AOT-CTA RMs, in AOT-BHD RMs this process is inhibited due to a specific interaction between HC and the polar head group of the BHD+ cation. This implies that the chemical structure of CTA+ and BHD+ cations has a large impact on the excited stated from which HC emission occurs. Additionally, the structural difference between the two cations impacts on the water-RM interface interaction, which provides a way of controlling the solvation process in these RMs. Furthermore, differences in the interfacial fluidity between the two catanionic RMs is observed, a result that is particularly interesting with regard to these systems being used as nanoreactors.
Collapse
|
15
|
Wang J, Sun R, Hao C, Li T, Tian Y, Zhang L. Influence of metal cations and cholesterol on lipid-amphotericin membrane. Chem Res Chin Univ 2017. [DOI: 10.1007/s40242-017-6303-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
16
|
Crosio MA, Silber JJ, Moyano F, Correa NM, Falcone RD. The Use of AOBH-DEHP Molecular Probe to Characterize BHDC Reverse Micelles Interfaces. Insights on the Interfacial Water Structure. ChemistrySelect 2017. [DOI: 10.1002/slct.201700361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Matías A. Crosio
- Departamento de Química; Universidad Nacional de Río Cuarto, Agencia Postal # 3. ( X5804ZAB ); Río Cuarto Argentina
| | - Juana J. Silber
- Departamento de Química; Universidad Nacional de Río Cuarto, Agencia Postal # 3. ( X5804ZAB ); Río Cuarto Argentina
| | - Fernando Moyano
- Departamento de Química; Universidad Nacional de Río Cuarto, Agencia Postal # 3. ( X5804ZAB ); Río Cuarto Argentina
| | - N. Mariano Correa
- Departamento de Química; Universidad Nacional de Río Cuarto, Agencia Postal # 3. ( X5804ZAB ); Río Cuarto Argentina
| | - R. Darío Falcone
- Departamento de Química; Universidad Nacional de Río Cuarto, Agencia Postal # 3. ( X5804ZAB ); Río Cuarto Argentina
| |
Collapse
|
17
|
Kundu P, Banerjee D, Maiti G, Chattopadhyay N. Dehydrogenation induced inhibition of intramolecular charge transfer in substituted pyrazoline analogues. Phys Chem Chem Phys 2017; 19:11937-11946. [DOI: 10.1039/c7cp01121k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experimental and computational studies reveal that dehydrogenation of the pyrazoline ring modifies its ground and excited state photophysics radically by restricting the ICT process.
Collapse
Affiliation(s)
- Pronab Kundu
- Department of Chemistry
- Jadavpur University
- Kolkata-700032
- India
| | | | - Gourhari Maiti
- Department of Chemistry
- Jadavpur University
- Kolkata-700032
- India
| | | |
Collapse
|
18
|
Amaro M, Filipe HAL, Prates Ramalho JP, Hof M, Loura LMS. Fluorescence of nitrobenzoxadiazole (NBD)-labeled lipids in model membranes is connected not to lipid mobility but to probe location. Phys Chem Chem Phys 2016; 18:7042-54. [PMID: 26727975 DOI: 10.1039/c5cp05238f] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Nitrobenzoxadiazole (NBD)-labeled lipids are popular fluorescent membrane probes. However, the understanding of important aspects of the photophysics of NBD remains incomplete, including the observed shift in the emission spectrum of NBD-lipids to longer wavelengths following excitation at the red edge of the absorption spectrum (red-edge excitation shift or REES). REES of NBD-lipids in membrane environments has been previously interpreted as reflecting restricted mobility of solvent surrounding the fluorophore. However, this requires a large change in the dipole moment (Δμ) of NBD upon excitation. Previous calculations of the value of Δμ of NBD in the literature have been carried out using outdated semi-empirical methods, leading to conflicting values. Using up-to-date density functional theory methods, we recalculated the value of Δμ and verified that it is rather small (∼2 D). Fluorescence measurements confirmed that the value of REES is ∼16 nm for 1,2-dioleoyl-sn-glycero-3-phospho-l-serine-N-(NBD) (NBD-PS) in dioleoylphosphatidylcholine vesicles. However, the observed shift is independent of both the temperature and the presence of cholesterol and is therefore insensitive to the mobility and hydration of the membrane. Moreover, red-edge excitation leads to an increased contribution of the decay component with a shorter lifetime, whereas time-resolved emission spectra of NBD-PS displayed an atypical blue shift following excitation. This excludes restrictions to solvent relaxation as the cause of the measured REES and TRES of NBD, pointing instead to the heterogeneous transverse location of probes as the origin of these effects. The latter hypothesis was confirmed by molecular dynamics simulations, from which the calculated heterogeneity of the hydration and location of NBD correlated with the measured fluorescence lifetimes/REES. Globally, our combination of theoretical and experiment-based techniques has led to a considerably improved understanding of the photophysics of NBD and a reinterpretation of its REES in particular.
Collapse
Affiliation(s)
- Mariana Amaro
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 3, 182 23 Prague, Czech Republic.
| | - Hugo A L Filipe
- Centro de Química de Coimbra, Largo D. Dinis, Rua Larga, 3004-535 Coimbra, Portugal. and Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Largo D. Dinis, Rua Larga, 3004-535 Coimbra, Portugal and Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004-504 Coimbra, Portugal
| | - J P Prates Ramalho
- Departamento de Química and Centro de Química de Évora, Escola de Ciências e Tecnologia, Universidade de Évora, Rua Romão Ramalho, 59, 7000-671 Évora, Portugal
| | - Martin Hof
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 3, 182 23 Prague, Czech Republic.
| | - Luís M S Loura
- Centro de Química de Coimbra, Largo D. Dinis, Rua Larga, 3004-535 Coimbra, Portugal. and Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004-504 Coimbra, Portugal and Faculdade de Farmácia, Universidade de Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| |
Collapse
|
19
|
Yenupuri TV, Mydlova L, Agarwal DS, Sharma R, Sakhuja R, Makowska-Janusik M, Pant DD. Experimental and Quantum Chemical Calculations of Imidazolium Appended Naphthalene Hybrid in Different Biomimicking Aqueous Interfaces. J Phys Chem A 2016; 120:6563-74. [DOI: 10.1021/acs.jpca.6b05864] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tej Varma Yenupuri
- Department
of Physics, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India
| | - Lucia Mydlova
- Institute
of Physics, Faculty of Mathematics and Natural Science, Jan Dlugosz University, Al. Armii Krajowej 13/15, 42-200 Czestochowa, Poland
| | - Devesh S. Agarwal
- Department
of Chemistry, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India
| | - Ritika Sharma
- Department
of Physics, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India
| | - Rajeev Sakhuja
- Department
of Chemistry, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India
| | - Malgorzata Makowska-Janusik
- Institute
of Physics, Faculty of Mathematics and Natural Science, Jan Dlugosz University, Al. Armii Krajowej 13/15, 42-200 Czestochowa, Poland
| | - Debi D. Pant
- Department
of Physics, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India
| |
Collapse
|
20
|
Kundu P, Ghosh S, Karmakar R, Maiti G, Chattopadhyay N. Impact of Structural Modification on the Photophysical Response of Benzoquinoline Fluorophores. J Fluoresc 2016; 26:845-54. [DOI: 10.1007/s10895-016-1772-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 01/14/2016] [Indexed: 10/22/2022]
|
21
|
Luna MA, Correa NM, Silber JJ, Falcone RD, Moyano F. Properties of AOT reverse micelle interfaces with different polar solvents. J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3535] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- M. Alejandra Luna
- Departamento de Química; Universidad Nacional de Río Cuarto; Agencia Postal # 3. C.P. X5804BYA Río Cuarto Argentina
| | - N. Mariano Correa
- Departamento de Química; Universidad Nacional de Río Cuarto; Agencia Postal # 3. C.P. X5804BYA Río Cuarto Argentina
| | - Juana J. Silber
- Departamento de Química; Universidad Nacional de Río Cuarto; Agencia Postal # 3. C.P. X5804BYA Río Cuarto Argentina
| | - R. Dario Falcone
- Departamento de Química; Universidad Nacional de Río Cuarto; Agencia Postal # 3. C.P. X5804BYA Río Cuarto Argentina
| | - Fernando Moyano
- Departamento de Química; Universidad Nacional de Río Cuarto; Agencia Postal # 3. C.P. X5804BYA Río Cuarto Argentina
| |
Collapse
|
22
|
Laguerre M, Bayrasy C, Panya A, Weiss J, McClements DJ, Lecomte J, Decker EA, Villeneuve P. What makes good antioxidants in lipid-based systems? The next theories beyond the polar paradox. Crit Rev Food Sci Nutr 2015; 55:183-201. [PMID: 24915410 DOI: 10.1080/10408398.2011.650335] [Citation(s) in RCA: 203] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The polar paradox states that polar antioxidants are more active in bulk lipids than their nonpolar counterparts, whereas nonpolar antioxidants are more effective in oil-in-water emulsion than their polar homologs. However, recent results, showing that not all antioxidants behave in a manner proposed by this hypothesis in oil and emulsion, lead us to revisit the polar paradox and to put forward new concepts, hypotheses, and theories. In bulk oil, new evidences have been brought to demonstrate that the crucial site of oxidation is not the air-oil interface, as postulated by the polar paradox, but association colloids formed with traces of water and surface active molecules such as phospholipids. The role of these association colloids on lipid oxidation and its inhibition by antioxidant is also addressed as well as the complex influence of the hydrophobicity on the ability of antioxidants to protect lipids from oxidation. In oil-in water emulsion, we have covered the recently discovered non linear (or cut-off) influence of the hydrophobicity on antioxidant capacity. For the first time, different mechanisms of action are formulated in details to try to account for this nonlinear effect. As suggested by the great amount of biological studies showing a cut-off effect, this phenomenon could be widespread in dispersed lipid systems including emulsions and liposomes as well as in living systems such as cultured cells. Works on the cut-off effect paves the way for the determination of the critical chain length which corresponds to the threshold beyond which antioxidant capacity suddenly collapses. The systematic search for this new physico-chemical parameter will allow designing novel phenolipids and other amphiphilic antioxidants in a rational fashion. Finally, in both bulk oils and emulsions, we feel that it is now time for a paradigm shift from the polar paradox to the next theories.
Collapse
|
23
|
Amirkavei M, Kinnunen PKJ. Interactions and dynamics of two extended conformation adapting phosphatidylcholines in model biomembranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:264-73. [PMID: 26656184 DOI: 10.1016/j.bbamem.2015.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 11/11/2015] [Accepted: 12/03/2015] [Indexed: 11/18/2022]
Abstract
In order to obtain molecular level insight into the biophysics of the apoptosis promoting phospholipid 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC) we studied its partitioning into different lipid phases by isothermal titration calorimetry (ITC). To aid the interpretation of these data for PazePC, we additionally characterized by both ITC and fluorescence spectroscopy the fluorescent phospholipid analog 1-palmitoyl-2-{6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl}-sn-glycero-3-phosphocholine (NBD-C6-PC), which similarly to PazePC can adopt extended conformation in lipid bilayers. With the NBD-hexanoyl chain reversing its direction and extending into the aqueous space out of the bilayer, 7-nitro-2,1,3-benzoxadiazol-4-yl (NBD) becomes accessible to the water soluble dithionite, which reduces to non-fluorescent product. Our results suggest that these phospholipid derivatives first partition and penetrate into the outer bilayer leaflet of liquid disordered phase liposomes composed of unsaturated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Upon increase up to 2 mol% PazePC and NBD-C6-PC of the overall content, flip-flop from the outer into the inner bilayer leaflet commences. Interestingly, the presence of 40 mol% cholesterol in POPC liposomes did not abrogate the partitioning of PazePC into the liquid ordered phase. In contrast, only insignificant partitioning of PazePC and NBD-C6-PC into sphingomyelin/cholesterol liposomes was evident, highlighting a specific membrane permeability barrier function of this particular lipid composition against oxidatively truncated PazePC, thus emphasizing the importance of detailed characterization of the biophysical properties of membranes found in different cellular organelles, in terms of providing barriers for lipid-mediated cellular signals in processes such as apoptosis. Our data suggest NBD-C6-PC to represent useful fluorescent probe to study the cellular dynamics of oxidized phospholipid species, such as PazePC.
Collapse
Affiliation(s)
- Mooud Amirkavei
- Helsinki Biophysics & Biomembrane group, Department of Neuroscience and Biomedical Engineering, School of Science, Aalto University, Espoo, Finland
| | - Paavo K J Kinnunen
- Helsinki Biophysics & Biomembrane group, Department of Neuroscience and Biomedical Engineering, School of Science, Aalto University, Espoo, Finland.
| |
Collapse
|
24
|
Cui L, McClements DJ, Decker EA. Impact of phosphatidylethanolamine on the antioxidant activity of α-tocopherol and trolox in bulk oil. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:3288-3294. [PMID: 25768290 DOI: 10.1021/acs.jafc.5b00243] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The amphiphilic phospholipids dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylethanolamine (DOPE), can form reverse micelles in bulk oils, which affects lipid oxidation chemistry. Previous studies showed that reverse micelles formed by DOPC and DOPE shorten the oxidation lag phase of stripped soybean oil. This study examined how these reverse micelles influence the activity of primary antioxidants such as the nonpolar α-tocopherol and the polar trolox in stripped and commercial soybean oils. The results showed that DOPC reverse micelles decreased the activity of 100 μM α-tocopherol or trolox. On the other hand, DOPE increased the antioxidant activity of both α-tocopherol and trolox. The polar trolox exhibited better antioxidant activity than the nonpolar α-tocopherol in the presence of both DOPC and DOPE reverse micelles because trolox partitioned more at the interfaces, which was confirmed by a fluorescence steady state study. Different ratios of DOPE to DOPC were added to oil containing 100 μM α-tocopherol, and antioxidant activity increased with increasing DOPE/DOPC ratio. Addition of DOPE to commercial oil inhibited lipid oxidation, whetrsd DOPC was ineffective. HPLC showed that DOPE regenerated α-tocopherol. This study indicates that the antioxidant activity of tocopherols could be improved by utilizing phosphatidylethanolamine (PE) to engineer the properties of reverse micelles in bulk oil.
Collapse
Affiliation(s)
- Leqi Cui
- †Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - D Julian McClements
- †Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003, United States
- §Bioactive Natural Products Research Group, Department of Biochemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
| | - Eric A Decker
- †Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003, United States
- §Bioactive Natural Products Research Group, Department of Biochemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
| |
Collapse
|
25
|
Villa CC, Correa NM, Silber JJ, Moyano F, Falcone RD. Singularities in the physicochemical properties of spontaneous AOT-BHD unilamellar vesicles in comparison with DOPC vesicles. Phys Chem Chem Phys 2015; 17:17112-21. [DOI: 10.1039/c5cp02387d] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
AOT-BHD vesicles present a bilayer completely different to the traditional DOPC vesicles, with low polarity, high viscosity and more electron donor capacity.
Collapse
Affiliation(s)
- Cristian C. Villa
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto
- Argentina
| | - N. Mariano Correa
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto
- Argentina
| | - Juana J. Silber
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto
- Argentina
| | - Fernando Moyano
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto
- Argentina
| | - R. Darío Falcone
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto
- Argentina
| |
Collapse
|
26
|
Demchenko AP, Duportail G, Oncul S, Klymchenko AS, Mély Y. Introduction to fluorescence probing of biological membranes. Methods Mol Biol 2015; 1232:19-43. [PMID: 25331125 DOI: 10.1007/978-1-4939-1752-5_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fluorescence is one of the most powerful and commonly used tools in biophysical studies of biomembrane structure and dynamics that can be applied on different levels, from lipid monolayers and bilayers to living cells, tissues, and whole animals. Successful application of this method relies on proper design of fluorescence probes with optimized photophysical properties. These probes are efficient for studying the microscopic analogs of viscosity, polarity, and hydration, as well as the molecular order, environment relaxation, and electrostatic potentials at the sites of their location. Being smaller than the membrane width they can sense the gradients of these parameters across the membrane. We present examples of novel dyes that achieve increased spatial resolution and information content of the probe responses. In this respect, multiparametric environment-sensitive probes feature considerable promise.
Collapse
Affiliation(s)
- Alexander P Demchenko
- Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, 9 Leontovicha Street, Kiev, 01030, Ukraine,
| | | | | | | | | |
Collapse
|
27
|
Association Colloids Formed by Multiple Surface Active Minor Components and Their Effect on Lipid Oxidation in Bulk Oil. J AM OIL CHEM SOC 2014. [DOI: 10.1007/s11746-014-2541-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
|
28
|
Babu E, Muthu Mareeswaran P, Singaravadivel S, Bhuvaneswari J, Rajagopal S. A selective, long-lived deep-red emissive ruthenium(II) polypyridine complexes for the detection of BSA. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 130:553-60. [PMID: 24813285 DOI: 10.1016/j.saa.2014.04.060] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 04/02/2014] [Accepted: 04/10/2014] [Indexed: 05/13/2023]
Abstract
A selective, label free luminescence sensor for bovine serum albumin (BSA) is investigated using ruthenium(II) complexes over the other proteins. Interaction between BSA and ruthenium(II) complexes has been studied using absorption, emission, excited state lifetime and circular dichroism (CD) spectral techniques. The luminescence intensity of ruthenium(II) complexes (I and II), has enhanced at 602 and 613 nm with a large hypsochromic shift of 18 and 5 nm respectively upon addition of BSA. The mode of binding of ruthenium(II) complexes with BSA has analyzed using computational docking studies.
Collapse
Affiliation(s)
- Eththilu Babu
- Department of Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, Tamil Nadu, India; Department of Chemistry, VV College of Engineering, Tisaiyanvilai, Tirunelveli, India
| | - Paulpandian Muthu Mareeswaran
- Department of Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, Tamil Nadu, India; Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Subramanian Singaravadivel
- Department of Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, Tamil Nadu, India
| | - Jayaraman Bhuvaneswari
- Department of Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, Tamil Nadu, India; Department of Chemistry, SRI G.V.G Visalakshi College for Women, Udumalapet, Tamil Nadu, India
| | - Seenivasan Rajagopal
- Department of Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, Tamil Nadu, India.
| |
Collapse
|
29
|
Raghuraman H, Islam SM, Mukherjee S, Roux B, Perozo E. Dynamics transitions at the outer vestibule of the KcsA potassium channel during gating. Proc Natl Acad Sci U S A 2014; 111:1831-6. [PMID: 24429344 PMCID: PMC3918809 DOI: 10.1073/pnas.1314875111] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In K(+) channels, the selectivity filter, pore helix, and outer vestibule play a crucial role in gating mechanisms. The outer vestibule is an important structurally extended region of KcsA in which toxins, blockers, and metal ions bind and modulate the gating behavior of K(+) channels. Despite its functional significance, the gating-related structural dynamics at the outer vestibule are not well understood. Under steady-state conditions, inactivating WT and noninactivating E71A KcsA stabilize the nonconductive and conductive filter conformations upon opening the activation gate. Site-directed fluorescence polarization of 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-labeled outer vestibule residues shows that the outer vestibule of open/conductive conformation is highly dynamic compared with the motional restriction experienced by the outer vestibule during inactivation gating. A wavelength-selective fluorescence approach shows a change in hydration dynamics in inactivated and noninactivated conformations, and supports a possible role of restricted/bound water molecules in C-type inactivation gating. Using a unique restrained ensemble simulation method, along with distance measurements by EPR, we show that, on average, the outer vestibule undergoes a modest backbone conformational change during its transition to various functional states, although the structural dynamics of the outer vestibule are significantly altered during activation and inactivation gating. Taken together, our results support the role of a hydrogen bond network behind the selectivity filter, side-chain conformational dynamics, and water molecules in the gating mechanisms of K(+) channels.
Collapse
|
30
|
Steady-state and time-resolved spectroscopic investigations on the existence of stable methanol/AOT/n-heptane reverse micelles. J Colloid Interface Sci 2014; 423:1-6. [PMID: 24703660 DOI: 10.1016/j.jcis.2013.12.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/07/2013] [Accepted: 12/20/2013] [Indexed: 11/23/2022]
Abstract
In this work, we have reported our study on the controversial issue whether methanol molecules can be effectively encapsulated by surfactant AOT to form true reverse micelles. We compared the different photophysical properties of coumarin 153 (C153) in methanol/AOT/n-heptane reverse micelles and methanol/n-heptane binary mixture by means of steady-state absorption, fluorescence and time-resolved fluorescence spectroscopies. In the reverse micelles, the fluorescence emission spectra of C153 were dependent on the excitation wavelength, while in binary mixtures, the excitation wavelength dependence was not observed. The biexponential decay curves of C153 in reverse micelles give a further confirmation for the two different environments where C153 molecules reside in. In other words, C153 molecules can exist both inside the core of the reverse micelles and outside of it. These results proved that the methanol can be effectively encapsulated by AOT in n-heptane solvents to form stable methanol/AOT/n-heptane reverse micelles.
Collapse
|
31
|
Maity B, Chatterjee A, Seth D. The photophysics of 7-(diethylamino)coumarin-3-carboxylic acid N-succinimidyl ester in reverse micelle: excitation wavelength dependent dynamics. RSC Adv 2014. [DOI: 10.1039/c3ra44240c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
|
32
|
Zhang L, Ren XM, Guo LH. Structure-based investigation on the interaction of perfluorinated compounds with human liver fatty acid binding protein. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:11293-301. [PMID: 24006842 DOI: 10.1021/es4026722] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Perfluorinated compounds (PFCs) are known to accumulate in liver and induce hepatotoxicity on experimental animals. Liver fatty acid binding protein (L-FABP) is expressed highly in hepatocytes and binds fatty acids. PFCs may bind with FABP and change their ADME and toxicity profile. In the present study, the binding interaction of 17 structurally diverse PFCs with human L-FABP was investigated to assess their potential disruption effect on fatty acid binding. The binding affinity of twelve perfluorinated carboxylic acids (PFCAs), as determined by fluorescence displacement assay, increased significantly with their carbon number from 4 to 11, and decreased slightly when the number was over 11. The three perfluorinated sulfonic acids (PFSAs) displayed comparable affinity, but no binding was detected for the two fluorotelomer alcohols. Circular dichroism results showed that PFC binding induced distinctive structural changes of the protein. Molecular docking revealed that the driving forces for the binding of PFCs with FABP were predominantly hydrophobic and hydrogen-bonding interactions, and the binding geometry was dependent on both the size and rigidity of the PFCs. Based on the binding constant obtained in this work, the possibility of in vivo competitive displacement of fatty acids from FABP by PFCs was estimated.
Collapse
Affiliation(s)
- Lianying Zhang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , P.O. Box 2871, 18 Shuangqing Road, Beijing 100085, China
| | | | | |
Collapse
|
33
|
Amaro M, Brezovský J, Kováčová S, Maier L, Chaloupková R, Sýkora J, Paruch K, Damborský J, Hof M. Are Time-Dependent Fluorescence Shifts at the Tunnel Mouth of Haloalkane Dehalogenase Enzymes Dependent on the Choice of the Chromophore? J Phys Chem B 2013; 117:7898-906. [DOI: 10.1021/jp403708c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mariana Amaro
- J. Heyrovsky Institute of Physical
Chemistry of the ASCR, v. v. i., Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Praha, Czech
Republic
| | - Jan Brezovský
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Silvia Kováčová
- International Centre for Clinical
Research, St. Anne’s University Hospital Brno, Pekarska 53, 656 91 Brno, Czech Republic
- Department of Chemistry, Faculty
of Science, Masaryk University, Kamenice
5/A8, 625 00 Brno, Czech Republic
| | - Lukáš Maier
- International Centre for Clinical
Research, St. Anne’s University Hospital Brno, Pekarska 53, 656 91 Brno, Czech Republic
- Department of Chemistry, Faculty
of Science, Masaryk University, Kamenice
5/A8, 625 00 Brno, Czech Republic
| | - Radka Chaloupková
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Jan Sýkora
- J. Heyrovsky Institute of Physical
Chemistry of the ASCR, v. v. i., Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Praha, Czech
Republic
| | - Kamil Paruch
- International Centre for Clinical
Research, St. Anne’s University Hospital Brno, Pekarska 53, 656 91 Brno, Czech Republic
- Department of Chemistry, Faculty
of Science, Masaryk University, Kamenice
5/A8, 625 00 Brno, Czech Republic
| | - Jiří Damborský
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
- International Centre for Clinical
Research, St. Anne’s University Hospital Brno, Pekarska 53, 656 91 Brno, Czech Republic
| | - Martin Hof
- J. Heyrovsky Institute of Physical
Chemistry of the ASCR, v. v. i., Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Praha, Czech
Republic
| |
Collapse
|
34
|
Bhattacharya P, Chakravorti S. Spectral features of 4,4-diaminodiphenyl sulfone in anionic and cationic inverted micelles. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
35
|
Chatterjee A, Maity B, Seth D. The photophysics of 7-(N,N′-diethylamino)coumarin-3-carboxylic acid in water/AOT/isooctane reverse micelles: an excitation wavelength dependent study. Phys Chem Chem Phys 2013; 15:1894-906. [DOI: 10.1039/c2cp43483k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
36
|
Locations of methanol in methanol-containing AOT reverse micelles revealed by photophysics of IR125. J Photochem Photobiol A Chem 2013. [DOI: 10.1016/j.jphotochem.2012.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
37
|
|
38
|
Application of NBD-Labeled Lipids in Membrane and Cell Biology. SPRINGER SERIES ON FLUORESCENCE 2012. [DOI: 10.1007/4243_2012_43] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
39
|
Valle L, Morán Vieyra FE, Borsarelli CD. Hydrogen-bonding modulation of excited-state properties of flavins in a model of aqueous confined environment. Photochem Photobiol Sci 2012; 11:1051-61. [DOI: 10.1039/c2pp05385c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
40
|
Ferreyra DD, Correa NM, Silber JJ, Falcone RD. The effect of different interfaces and confinement on the structure of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide entrapped in cationic and anionic reverse micelles. Phys Chem Chem Phys 2012; 14:3460-70. [DOI: 10.1039/c2cp23481e] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
41
|
Quintana SS, Falcone RD, Silber JJ, Correa NM. Comparison between Two Anionic Reverse Micelle Interfaces: The Role of Water-Surfactant Interactions in Interfacial Properties. Chemphyschem 2011; 13:115-23. [DOI: 10.1002/cphc.201100638] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 10/21/2011] [Indexed: 11/12/2022]
|
42
|
|
43
|
Bhuvaneswari J, Mareeswaran PM, Shanmugasundaram S, Rajagopal S. Protein binding studies of luminescent rhenium(I) diimine complexes. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2011.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
44
|
Haldar S, Chaudhuri A, Chattopadhyay A. Organization and dynamics of membrane probes and proteins utilizing the red edge excitation shift. J Phys Chem B 2011; 115:5693-706. [PMID: 21428321 DOI: 10.1021/jp200255e] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dynamics of confined water has interesting implications in the organization and function of molecular assemblies such as membranes. A direct consequence of this type of organization is the restriction imposed on the mobility of the constituent structural units. Interestingly, this restriction (confinement) of mobility couples the motion of solvent (water) molecules with the slow moving molecules in the assembly. It is in this context that the red edge excitation shift (REES) represents a sensitive approach to monitor the environment and dynamics around a fluorophore in such organized assemblies. A shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of the absorption band, is termed REES. REES relies on slow solvent reorientation in the excited state of a fluorophore that can be used to monitor the environment and dynamics around a fluorophore in a host assembly. In this article, we focus on the application of REES to monitor organization and dynamics of membrane probes and proteins.
Collapse
Affiliation(s)
- Sourav Haldar
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007 India
| | | | | |
Collapse
|
45
|
Blach D, Correa NM, Silber JJ, Falcone RD. Interfacial water with special electron donor properties: Effect of water–surfactant interaction in confined reversed micellar environments and its influence on the coordination chemistry of a copper complex. J Colloid Interface Sci 2011; 355:124-30. [DOI: 10.1016/j.jcis.2010.11.067] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Revised: 11/19/2010] [Accepted: 11/20/2010] [Indexed: 10/18/2022]
|
46
|
Chen B, Han A, Laguerre M, McClements DJ, Decker EA. Role of reverse micelles on lipid oxidation in bulk oils: impact of phospholipids on antioxidant activity of α-tocopherol and Trolox. Food Funct 2011; 2:302-9. [DOI: 10.1039/c1fo10046g] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
47
|
Zhu R, Lu R, Yu A. Photophysics and locations of IR125 and C152 in AOT reverse micelles. Phys Chem Chem Phys 2011; 13:20844-54. [DOI: 10.1039/c1cp21946d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
48
|
Fluorescence Probing in Structurally Anisotropic Materials. ADVANCED FLUORESCENCE REPORTERS IN CHEMISTRY AND BIOLOGY III 2011. [DOI: 10.1007/978-3-642-18035-4_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
49
|
Chen B, Han A, McClements DJ, Decker EA. Physical structures in soybean oil and their impact on lipid oxidation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:11993-9. [PMID: 20964436 DOI: 10.1021/jf102763p] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The oxidation of edible oil yields both primary and secondary oxidation products (e.g., hydroperoxides, carbonyls, hydrocarbons, and epoxides), which produce undesirable sensory and biological effects. Consequently, the suppression of lipid oxidation in food matrices is of great importance. The rate and extent of lipid oxidation in many heterogeneous foods are strongly affected by the physicochemical characteristics of water-oil interfaces. This study examined the ability of dioleoylphosphatidylcholine (DOPC) and water to form association colloids within bulk oil, as well as their impact on lipid oxidation kinetics. Attenuation was used to show the DOPC and water concentrations at which association colloids existed without altering the optical properties of the oil. Interfacial tension and fluorescence spectrometry showed the critical micelle concentration (CMC) of DOPC in stripped soybean oil was around 650 μM at room temperature. Small-angle X-ray scattering (SAXS) and fluorescence probes showed that water had a very strong impact on the properties of the association colloids formed by DOPC. Measurement of primary and secondary lipid oxidation products revealed that the association colloids formed by DOPC had a pro-oxidant effect. The characterization of association colloids could provide a better understanding of the mechanisms of lipid oxidation in bulk oils and provide insights into new antioxidant technologies.
Collapse
Affiliation(s)
- Bingcan Chen
- Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | | | | | | |
Collapse
|
50
|
Transbilayer organization of membrane cholesterol at low concentrations: Implications in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:19-25. [PMID: 21035427 DOI: 10.1016/j.bbamem.2010.10.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 10/20/2010] [Accepted: 10/22/2010] [Indexed: 02/06/2023]
Abstract
Cholesterol is an essential and representative lipid in higher eukaryotic cellular membranes and is often found distributed nonrandomly in domains in biological membranes. A large body of literature exists on the organization of cholesterol in plasma membranes or membranes with high cholesterol content. However, very little is known about organization of cholesterol in membranes containing low amounts of cholesterol such as the endoplasmic reticulum or inner mitochondrial membranes. In this review, we have traced the discovery and subsequent development of the concept of transbilayer cholesterol dimers (domains) in membranes at low concentrations. We have further discussed the role of membrane curvature and thickness on the transbilayer organization of cholesterol. Interestingly, this type of cholesterol organization could be relevant in cellular sorting and trafficking, and in pathological conditions.
Collapse
|