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Ghanimi Fard M, Khabir Z, Reineck P, Cordina NM, Abe H, Ohshima T, Dalal S, Gibson BC, Packer NH, Parker LM. Targeting cell surface glycans with lectin-coated fluorescent nanodiamonds. Nanoscale Adv 2022; 4:1551-1564. [PMID: 36134370 PMCID: PMC9418452 DOI: 10.1039/d2na00036a] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/06/2022] [Indexed: 06/02/2023]
Abstract
Glycosylation is arguably the most important functional post-translational modification in brain cells and abnormal cell surface glycan expression has been associated with neurological diseases and brain cancers. In this study we developed a novel method for uptake of fluorescent nanodiamonds (FND), carbon-based nanoparticles with low toxicity and easily modifiable surfaces, into brain cell subtypes by targeting their glycan receptors with carbohydrate-binding lectins. Lectins facilitated uptake of 120 nm FND with nitrogen-vacancy centers in three types of brain cells - U87-MG astrocytes, PC12 neurons and BV-2 microglia cells. The nanodiamond/lectin complexes used in this study target glycans that have been described to be altered in brain diseases including sialic acid glycans via wheat (Triticum aestivum) germ agglutinin (WGA), high mannose glycans via tomato (Lycopersicon esculentum) lectin (TL) and core fucosylated glycans via Aleuria aurantia lectin (AAL). The lectin conjugated nanodiamonds were taken up differently by the various brain cell types with fucose binding AAL/FNDs taken up preferentially by glioblastoma phenotype astrocyte cells (U87-MG), sialic acid binding WGA/FNDs by neuronal phenotype cells (PC12) and high mannose binding TL/FNDs by microglial cells (BV-2). With increasing recognition of glycans having a role in many diseases, the lectin bioconjugated nanodiamonds developed here are well suited for further investigation into theranostic applications.
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Affiliation(s)
- Mina Ghanimi Fard
- School of Natural Sciences, Centre of Excellence for Nanoscale BioPhotonics, Macquarie University Sydney NSW 2109 Australia +61 2 9850 8269
| | - Zahra Khabir
- School of Natural Sciences, Centre of Excellence for Nanoscale BioPhotonics, Macquarie University Sydney NSW 2109 Australia +61 2 9850 8269
| | - Philipp Reineck
- ARC Centre of Excellence for Nanoscale BioPhotonics, School of Science, RMIT University Melbourne VIC 3001 Australia
| | - Nicole M Cordina
- School of Natural Sciences, Centre of Excellence for Nanoscale BioPhotonics, Macquarie University Sydney NSW 2109 Australia +61 2 9850 8269
| | - Hiroshi Abe
- Quantum Beam Science Research Directorate, The Institute for Quantum Life Science, National Institutes for Quantum Science and Technology Takasaki Gunma 3701292 Japan
| | - Takeshi Ohshima
- Quantum Beam Science Research Directorate, The Institute for Quantum Life Science, National Institutes for Quantum Science and Technology Takasaki Gunma 3701292 Japan
| | - Sagar Dalal
- School of Natural Sciences, Centre of Excellence for Nanoscale BioPhotonics, Macquarie University Sydney NSW 2109 Australia +61 2 9850 8269
| | - Brant C Gibson
- ARC Centre of Excellence for Nanoscale BioPhotonics, School of Science, RMIT University Melbourne VIC 3001 Australia
| | - Nicolle H Packer
- School of Natural Sciences, Centre of Excellence for Nanoscale BioPhotonics, Macquarie University Sydney NSW 2109 Australia +61 2 9850 8269
- Institute for Glycomics, Griffith University Southport QLD 4222 Australia
| | - Lindsay M Parker
- School of Natural Sciences, Centre of Excellence for Nanoscale BioPhotonics, Macquarie University Sydney NSW 2109 Australia +61 2 9850 8269
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Kachooei E, Cordina NM, Potluri PR, Guse JA, McCamey D, Brown LJ. Phosphorylation of Troponin I finely controls the positioning of Troponin for the optimal regulation of cardiac muscle contraction. J Mol Cell Cardiol 2020; 150:44-53. [PMID: 33080242 DOI: 10.1016/j.yjmcc.2020.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 09/22/2020] [Accepted: 10/14/2020] [Indexed: 12/01/2022]
Abstract
Troponin is the Ca2+ molecular switch that regulates striated muscle contraction. In the heart, troponin Ca2+ sensitivity is also modulated by the PKA-dependent phosphorylation of a unique 31-residue N-terminal extension region of the Troponin I subunit (NH2-TnI). However, the detailed mechanism for the propagation of the phosphorylation signal through Tn, which results in the enhancement of the myocardial relaxation rate, is difficult to examine within whole Tn. Several models exist for how phosphorylation modulates the troponin response in cardiac cells but these are mostly built from peptide-NMR studies and molecular dynamics simulations. Here we used a paramagnetic spin labeling approach to position and track the movement of the NH2-TnI region within whole Tn. Through paramagnetic relaxation enhancement (PRE)-NMR experiments, we show that the NH2-TnI region interacts with a broad surface area on the N-domain of the Troponin C subunit. This region includes the Ca2+ regulatory Site II and the TnI switch-binding site. Phosphorylation of the NH2-TnI both weakens and shifts this region to an adjacent site on TnC. Interspin EPR distances between NH2-TnI and TnC further reveal a phosphorylation induced re-orientation of the TnC N-domain under saturating Ca2+ conditions. We propose an allosteric model where phosphorylation triggered cooperative changes in both the interaction of the NH2-TnI region with TnC, and the re-orientation of the TnC interdomain orientation, together promote the release of the TnI switch-peptide. Enhancement of the myocardial relaxation rate then occurs. Knowledge of this unique role of phosphorylation in whole Tn is important for understanding pathological processes affecting the heart.
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Affiliation(s)
- Ehsan Kachooei
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Nicole M Cordina
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Phani R Potluri
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Joanna A Guse
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Dane McCamey
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
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3
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Abstract
The fabrication of lectin-SERS nanotags and the assay designed for rapid glycoprotein identification and quantification.
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Affiliation(s)
| | - Wei Zhang
- Department of Molecular Sciences
- Macquarie University
- Australia
- ARC Centre of Excellence for Nanoscale BioPhotonics
- Macquarie University
| | - Nicolle H. Packer
- Department of Molecular Sciences
- Macquarie University
- Australia
- ARC Centre of Excellence for Nanoscale BioPhotonics
- Macquarie University
| | - Yuling Wang
- Department of Molecular Sciences
- Macquarie University
- Australia
- ARC Centre of Excellence for Nanoscale BioPhotonics
- Macquarie University
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4
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Kachooei E, Cordina NM, Brown LJ. Constructing a structural model of troponin using site-directed spin labeling: EPR and PRE-NMR. Biophys Rev 2019; 11:621-639. [PMID: 31321733 PMCID: PMC6682194 DOI: 10.1007/s12551-019-00568-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/24/2019] [Indexed: 02/05/2023] Open
Abstract
The relative ease of introducing a paramagnetic species onto a protein, and advances in electron paramagnetic resonance (EPR) over the past two decades, have established spin labeling as a vital structural biology technique for revealing the functional workings of the troponin muscle regulatory complex-an ~80 kDa heterotrimeric protein switch for turning on striated muscle contraction. Through the site-directed spin labeling (SDSL) of cysteine residues at key sites in troponin, a molecular-level understanding of the troponin muscle regulatory system across all levels of structural hierarchy has been achieved. Through the application of EPR, mobility and accessibility trends in the EPR signals of the spin labels attached to consecutive residues can reveal the secondary structure of troponin elements and also help map the interaction between subunits. Distance restraints calculated from the interspin interactions between spin label pairs have helped with building a structural model of the troponin complex. Further, when SDSL is paired with NMR, paramagnetic relaxation enhancement (PRE)-NMR has been used to obtain high-resolution structural detail for both intra- and interdomain interactions in troponin and revealed details of protein conformational changes and dynamics accompanying troponin function. In this review, we provide an overview of the SDSL labeling methodology and its application towards building a dynamic structural model of the multi-subunit troponin complex which details the calcium-induced conformational changes intimately linked to muscle regulation. We also describe how the SDSL method, in conjunction with EPR or NMR, can be used to obtain insights into structural perturbations to troponin caused by disease-causing mutations.
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Affiliation(s)
- Ehsan Kachooei
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Nicole M Cordina
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia.
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Potluri PR, Cordina NM, Kachooei E, Brown LJ. Characterization of the L29Q Hypertrophic Cardiomyopathy Mutation in Cardiac Troponin C by Paramagnetic Relaxation Enhancement Nuclear Magnetic Resonance. Biochemistry 2019; 58:908-917. [PMID: 30620548 DOI: 10.1021/acs.biochem.8b01140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The key events in regulating muscle contraction involve the troponin (Tn) heterotrimeric protein complex in which the binding to and release of Ca2+ from the highly conserved troponin C (TnC) subunit trigger a series of structural changes within Tn, and the other thin filament proteins, to result in contraction. In the heart, the control of contraction and relaxation events can be altered by many single-point mutations that may result in cardiomyopathy and sometimes sudden cardiac death. Here we have examined the structural effects of one hypertrophic cardiomyopathy mutation, L29Q, on Ca2+-induced structural transitions within whole TnC. This mutation is of particular interest as several physiological and structural studies have indicated that the response of TnC to Ca2+ binding is altered in the presence of the L29Q mutation, but the structural nature of these changes continues to be debated. In addition, little is known about the effect of this mutation in the Ca2+ free state. Here we have used paramagnetic relaxation enhancement nuclear magnetic resonance (PRE-NMR) to assess the structural effects arising from the L29Q mutation. PRE-NMR distances obtained from a nitroxide spin-label at Cys84 showed that the L29Q mutation perturbs the structure of the TnC N-domain in the presence and absence of Ca2+, with a more "open" TnC N-domain observed in the apo form. In addition, binding of Ca2+ to the TnC-L29Q construct triggers a change in the orientation between the two domains of TnC. Together, these structural perturbations, revealed by PRE-NMR, provide insight into the pathogenesis of this mutation.
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Affiliation(s)
- Phani R Potluri
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
| | - Nicole M Cordina
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
| | - Ehsan Kachooei
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
| | - Louise J Brown
- Department of Molecular Sciences , Macquarie University , Sydney , NSW 2109 , Australia
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Potluri PR, Chamoun J, Cooke JA, Badr M, Guse JA, Rayes R, Cordina NM, McCamey D, Fajer PG, Brown LJ. The concerted movement of the switch region of Troponin I in cardiac muscle thin filaments as tracked by conventional and pulsed (DEER) EPR. J Struct Biol 2017; 200:376-387. [DOI: 10.1016/j.jsb.2017.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/03/2017] [Accepted: 08/28/2017] [Indexed: 10/18/2022]
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Bradac C, Say JM, Rastogi ID, Cordina NM, Volz T, Brown LJ. Nano-assembly of nanodiamonds by conjugation to actin filaments. J Biophotonics 2016; 9:296-304. [PMID: 26296437 DOI: 10.1002/jbio.201500167] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/01/2015] [Accepted: 08/03/2015] [Indexed: 06/04/2023]
Abstract
Fluorescent nanodiamonds (NDs) are remarkable objects. They possess unique mechanical and optical properties combined with high surface areas and controllable surface reactivity. They are non-toxic and hence suited for use in biological environments. NDs are also readily available and commercially inexpensive. Here, the exceptional capability of controlling and tailoring their surface chemistry is demonstrated. Small, bright diamond nanocrystals (size ˜30 nm) are conjugated to protein filaments of actin (length ˜3-7 µm). The conjugation to actin filaments is extremely selective and highly target-specific. These unique features, together with the relative simplicity of the conjugation-targeting method, make functionalised nanodiamonds a powerful and versatile platform in biomedicine and quantum nanotechnologies. Applications ranging from using NDs as superior biological markers to, potentially, developing novel bottom-up approaches for the fabrication of hybrid quantum devices that would bridge across the bio/solid-state interface are presented and discussed.
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Affiliation(s)
- Carlo Bradac
- ARC Centre of Excellence for Engineered Quantum Systems (EQuS), Department of Physics and Astronomy, Macquarie University, Sydney, NSW, 2109, Australia
| | - Jana M Say
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Ishan D Rastogi
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Nicole M Cordina
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Thomas Volz
- ARC Centre of Excellence for Engineered Quantum Systems (EQuS), Department of Physics and Astronomy, Macquarie University, Sydney, NSW, 2109, Australia
| | - Louise J Brown
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
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Cordina NM, Liew CK, Potluri PR, Curmi PM, Fajer PG, Logan TM, Mackay JP, Brown LJ. Ca2+-induced PRE-NMR changes in the troponin complex reveal the possessive nature of the cardiac isoform for its regulatory switch. PLoS One 2014; 9:e112976. [PMID: 25392916 PMCID: PMC4231091 DOI: 10.1371/journal.pone.0112976] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 10/17/2014] [Indexed: 11/19/2022] Open
Abstract
The interaction between myosin and actin in cardiac muscle, modulated by the calcium (Ca2+) sensor Troponin complex (Tn), is a complex process which is yet to be fully resolved at the molecular level. Our understanding of how the binding of Ca2+ triggers conformational changes within Tn that are subsequently propagated through the contractile apparatus to initiate muscle activation is hampered by a lack of an atomic structure for the Ca2+-free state of the cardiac isoform. We have used paramagnetic relaxation enhancement (PRE)-NMR to obtain a description of the Ca2+-free state of cardiac Tn by describing the movement of key regions of the troponin I (cTnI) subunit upon the release of Ca2+ from Troponin C (cTnC). Site-directed spin-labeling was used to position paramagnetic spin labels in cTnI and the changes in the interaction between cTnI and cTnC subunits were then mapped by PRE-NMR. The functionally important regions of cTnI targeted in this study included the cTnC-binding N-region (cTnI57), the inhibitory region (cTnI143), and two sites on the regulatory switch region (cTnI151 and cTnI159). Comparison of 1H-15N-TROSY spectra of Ca2+-bound and free states for the spin labeled cTnC-cTnI binary constructs demonstrated the release and modest movement of the cTnI switch region (∼10 Å) away from the hydrophobic N-lobe of troponin C (cTnC) upon the removal of Ca2+. Our data supports a model where the non-bound regulatory switch region of cTnI is highly flexible in the absence of Ca2+ but remains in close vicinity to cTnC. We speculate that the close proximity of TnI to TnC in the cardiac complex is favourable for increasing the frequency of collisions between the N-lobe of cTnC and the regulatory switch region, counterbalancing the reduction in collision probability that results from the incomplete opening of the N-lobe of TnC that is unique to the cardiac isoform.
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Affiliation(s)
- Nicole M. Cordina
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Chu K. Liew
- Department of Molecular Cardiology and Biophysics, The Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Phani R. Potluri
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Paul M. Curmi
- School of Physics, The University of New South Wales, Sydney, New South Wales, Australia
| | - Piotr G. Fajer
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America
| | - Timothy M. Logan
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America
| | - Joel P. Mackay
- School of Molecular and Microbial Biosciences, University of Sydney, Sydney, New South Wales, Australia
| | - Louise J. Brown
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
- * E-mail:
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Cordina NM, Liew CK, Gell DA, Fajer PG, Mackay JP, Brown LJ. Effects of calcium binding and the hypertrophic cardiomyopathy A8V mutation on the dynamic equilibrium between closed and open conformations of the regulatory N-domain of isolated cardiac troponin C. Biochemistry 2013; 52:1950-62. [PMID: 23425245 DOI: 10.1021/bi4000172] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Troponin C (TnC) is the calcium-binding subunit of the troponin complex responsible for initiating striated muscle contraction in response to calcium influx. In the skeletal TnC isoform, calcium binding induces a structural change in the regulatory N-domain of TnC that involves a transition from a closed to open structural state and accompanying exposure of a large hydrophobic patch for troponin I (TnI) to subsequently bind. However, little is understood about how calcium primes the N-domain of the cardiac isoform (cTnC) for interaction with the TnI subunit as the open conformation of the regulatory domain of cTnC has been observed only in the presence of bound TnI. Here we use paramagnetic relaxation enhancement (PRE) to characterize the closed to open transition of isolated cTnC in solution, a process that cannot be observed by traditional nuclear magnetic resonance methods. Our PRE data from four spin-labeled monocysteine constructs of isolated cTnC reveal that calcium binding triggers movement of the N-domain helices toward an open state. Fitting of the PRE data to a closed to open transition model reveals the presence of a small population of cTnC molecules in the absence of calcium that possess an open conformation, the level of which increases substantially upon Ca(2+) binding. These data support a model in which calcium binding creates a dynamic equilibrium between the closed and open structural states to prime cTnC for interaction with its target peptide. We also used PRE data to assess the structural effects of a familial hypertrophic cardiomyopathy point mutation located within the N-domain of cTnC (A8V). The PRE data show that the Ca(2+) switch mechanism is perturbed by the A8V mutation, resulting in a more open N-domain conformation in both the apo and holo states.
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Affiliation(s)
- Nicole M Cordina
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
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Cordina NM, Liew CK, Gell DA, Fajer PG, Mackay JP, Brown LJ. Interdomain orientation of cardiac troponin C characterized by paramagnetic relaxation enhancement NMR reveals a compact state. Protein Sci 2013; 21:1376-87. [PMID: 22811351 DOI: 10.1002/pro.2124] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cardiac troponin C (cTnC) is the calcium binding subunit of the troponin complex that triggers the thin filament response to calcium influx into the sarcomere. cTnC consists of two globular EF-hand domains (termed the N- and C-domains) connected by a flexible linker. While the conformation of each domain of cTnC has been thoroughly characterized through NMR studies involving either the isolated N-domain (N-cTnC) or C-domain (C-cTnC), little attention has been paid to the range of interdomain orientations possible in full-length cTnC that arises as a consequence of the flexibility of the domain linker. Flexibility in the domain linker of cTnC is essential for effective regulatory function of troponin. We have therefore utilized paramagnetic relaxation enhancement (PRE) NMR to assess the interdomain orientation of cTnC. Ensemble fitting of our interdomain PRE measurements reveals that isolated cTnC has considerable interdomain flexibility and preferentially adopts a bent conformation in solution, with a defined range of relative domain orientations.
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Affiliation(s)
- Nicole M Cordina
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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Cordina NM, Liew CK, Gell DA, Cooke JA, Mackay J, Brown LJ. Structure and Dynamics of Cardiac Troponin C using Paramagnetic Relaxation Enhancement Derived Distances. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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