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Upadhya R, Murthy NS, Hoop CL, Kosuri S, Nanda V, Kohn J, Baum J, Gormley AJ. PET-RAFT and SAXS: High Throughput Tools to Study Compactness and Flexibility of Single-Chain Polymer Nanoparticles. Macromolecules 2019; 52:8295-8304. [PMID: 33814613 PMCID: PMC8018520 DOI: 10.1021/acs.macromol.9b01923] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
From protein science, it is well understood that ordered folding and 3D structure mainly arises from balanced and noncovalent polar and nonpolar interactions, such as hydrogen bonding. Similarly, it is understood that single-chain polymer nanoparticles (SCNPs) will also compact and become more rigid with greater hydrophobicity and intrachain hydrogen bonding. Here, we couple high throughput photoinduced electron/energy transfer reversible addition-fragmentation chain-transfer (PET-RAFT) polymerization with high throughput small-angle X-ray scattering (SAXS) to characterize a large combinatorial library (>450) of several homopolymers, random heteropolymers, block copolymers, PEG-conjugated polymers, and other polymer-functionalized polymers. Coupling these two high throughput tools enables us to study the major influence(s) for compactness and flexibility in higher breadth than ever before possible. Not surprisingly, we found that many were either highly disordered in solution, in the case of a highly hydrophilic polymer, or insoluble if too hydrophobic. Remarkably, we also found a small group (9/457) of PEG-functionalized random heteropolymers and block copolymers that exhibited compactness and flexibility similar to that of bovine serum albumin (BSA) by dynamic light scattering (DLS), NMR, and SAXS. In general, we found that describing a rough association between compactness and flexibility parameters (R g /R h and Porod Exponent, respectively) with logP, a quantity that describes hydrophobicity, helps to demonstrate and predict material parameters that lead to SCNPs with greater compactness, rigidity, and stability. Future implementation of this combinatorial and high throughput approach for characterizing SCNPs will allow for the creation of detailed design parameters for well-defined macromolecular chemistry.
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Affiliation(s)
- Rahul Upadhya
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - N. Sanjeeva Murthy
- New Jersey Center for Biomaterials, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Cody L. Hoop
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Shashank Kosuri
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Vikas Nanda
- Center for Advanced Biotechnology and Medicine, and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Joachim Kohn
- New Jersey Center for Biomaterials, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Jean Baum
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Adam J. Gormley
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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Tauchert MJ, Hémonnot C, Neumann P, Köster S, Ficner R, Dickmanns A. Impact of the crystallization condition on importin-β conformation. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:705-17. [DOI: 10.1107/s2059798316004940] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/23/2016] [Indexed: 11/10/2022]
Abstract
In eukaryotic cells, the exchange of macromolecules between the nucleus and cytoplasm is highly selective and requires specialized soluble transport factors. Many of them belong to the importin-β superfamily, the members of which share an overall superhelical structure owing to the tandem arrangement of a specific motif, the HEAT repeat. This structural organization leads to great intrinsic flexibility, which in turn is a prerequisite for the interaction with a variety of proteins and for its transport function. During the passage from the aqueous cytosol into the nucleus, the receptor passes the gated channel of the nuclear pore complex filled with a protein meshwork of unknown organization, which seems to be highly selective owing to the presence of FG-repeats, which are peptides with hydrophobic patches. Here, the structural changes of free importin-β from a single organism, crystallized in polar (salt) or apolar (PEG) buffer conditions, are reported. This allowed analysis of the structural changes, which are attributable to the surrounding milieu and are not affected by bound interaction partners. The importin-β structures obtained exhibit significant conformational changes and suggest an influence of the polarity of the environment, resulting in an extended conformation in the PEG condition. The significance of this observation is supported by SAXS experiments and the analysis of other crystal structures of importin-β deposited in the Protein Data Bank.
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Rajapaksha A, Stanley CB, Todd BA. Effects of macromolecular crowding on the structure of a protein complex: a small-angle scattering study of superoxide dismutase. Biophys J 2015; 108:967-974. [PMID: 25692601 PMCID: PMC4336365 DOI: 10.1016/j.bpj.2014.12.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/19/2014] [Accepted: 12/29/2014] [Indexed: 11/19/2022] Open
Abstract
Macromolecular crowding can alter the structure and function of biological macromolecules. We used small-angle scattering to measure the effects of macromolecular crowding on the size of a protein complex, SOD (superoxide dismutase). Crowding was induced using 400 MW PEG (polyethylene glycol),TEG (triethylene glycol), α-MG (methyl-α-glucoside), and TMAO (trimethylamine n-oxide). Parallel small-angle neutron scattering and small-angle x-ray scattering allowed us to unambiguously attribute apparent changes in radius of gyration to changes in the structure of SOD. For a 40% PEG solution, we find that the volume of SOD was reduced by 9%. Considering the osmotic pressure due to PEG, this deformation corresponds to a highly compressible structure. Small-angle x-ray scattering done in the presence of TEG suggests that for further deformation-beyond a 9% decrease in volume-the resistance to deformation may increase dramatically.
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Affiliation(s)
- Ajith Rajapaksha
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana
| | - Christopher B Stanley
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Brian A Todd
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana.
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Yu M, Ding Z, Jiang F, Ding X, Sun J, Chen S, Lv G. Analysis of binding interaction between pegylated puerarin and bovine serum albumin by spectroscopic methods and dynamic light scattering. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 83:453-460. [PMID: 21945127 DOI: 10.1016/j.saa.2011.08.065] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 08/25/2011] [Accepted: 08/27/2011] [Indexed: 05/31/2023]
Abstract
The interaction between bovine serum albumin (BSA) and pegylated puerarin (Pur) in aqueous solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy and circular dichroism spectra (CD), as well as dynamic light scattering (DLS). The fluorescence of BSA was strongly quenched by the binding of pegylated Pur to BSA. The binding constants and the number of binding sites of mPEG(5000)-Pur with BSA were 2.67±0.12 and 1.37±0.05 folds larger after pegylating, which were calculated from the data obtained from fluorescence quenching experiments. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be 4.09 kJ mol(-1) and 20.01 J mol(-1) K(-1), respectively, according to Van't Hoff equation, indicating that the hydrophobic force plays a main role in the binding interaction between pegylated Pur and BSA. In addition, the negative sign for Gibbs free energy change (ΔG) implies that the interaction process is spontaneous. Moreover, the results of synchronous fluorescence and CD spectra demonstrated that the microenvironment and the secondary conformation of BSA were changed. Comparing with Pur, all our data collected indicated that pegylated Pur interacted with BSA in the same way as that of Pur, but docked into the hydrophobic pocket of BSA with more accessibility and stronger binding force. DLS measurements showed monomethoxy polyethylene glycol (mPEG) have an effect on BSA conformation, and revealed that changes in BSA size might be due to increases in binding constant and the absolute values of ΔG after Pur pegylation.
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Affiliation(s)
- Meirong Yu
- Zhejiang Chinese Medical University, Hangzhou, PR China
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Hori K, Nishihara M, Shiraishi K, Yokoyama M. The Combretastatin Derivative (Cderiv), a Vascular Disrupting Agent, Enables Polymeric Nanomicelles to Accumulate in Microtumors. J Pharm Sci 2010; 99:2914-25. [DOI: 10.1002/jps.22038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Castelletto V, Hamley IW, Clifton LA, Green RJ. Osmotic pressure and aggregate shape in BSA/poly(ethylene glycol)-lipid/Dextran solutions. Biophys Chem 2008; 134:34-8. [DOI: 10.1016/j.bpc.2008.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 01/07/2008] [Accepted: 01/08/2008] [Indexed: 11/26/2022]
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Castelletto V, Krysmann MJ, Clifton LA, Lambourne J, Noirez L. Structural Study of BSA/Poly(ethylene glycol) Lipid Conjugate Complexes. J Phys Chem B 2007; 111:11330-6. [PMID: 17803303 DOI: 10.1021/jp074409n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work we report the structural characteristics of bovine serum albumin/poly(ethylene glycol) lipid conjugate (BSA/PEG(2000)-PE) complexes under physiological conditions (37 degrees C and pH 7.4) for particular fractions of BSA to PEG-lipid concentration, c(BSA)/c(PEG)(2000)-PE. Ultraviolet fluorescence spectroscopy (UV) results shown that PEG(2000)-PE is associated to BSA, leading to protein unfolding for fixed c(BSA) = 0.01 wt % and variable c(PEG)(2000)-PE = 0.0015-0.6 wt %. Tryptophan groups on the BSA surface are in contact with the PEG-lipid at c(PEG)(2000)-PE = 0.0015 wt %, while they are exposed to water at c(PEG)(2000)-PE > 0.0015 wt %. Dynamic and static light scattering (DLS and SLS) and small-angle neutron scattering (SANS) point out the existence of individual BSA/PEG-lipid complexes in the system for fixed c(BSA) = 1 wt % and variable c(PEG)(2000)-PE = 0.15-2 wt %. DLS shows that there is only one BSA molecule per protein/PEG-lipid complex, while SLS shows that the PEG-lipid associates to the BSA without promoting aggregation between adjacent protein/polymer-lipid conjugate complexes. SANS was used to show that BSA/PEG(2000)-PE complexes adopt an oblate ellipsoidal shape. Partially unfolded BSA is contained in the core of the oblate ellipsoid, which is surrounded by an external shell containing the PEG(2000)-PE.
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Affiliation(s)
- Valeria Castelletto
- School of Chemistry, Food Biosciences and Pharmacy, The University of Reading, PO BOX 226, Whiteknights, Reading RG6 6AP, United Kingdom.
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Castelletto V, Krysmann M, Kelarakis A, Jauregi P. Complex Formation of Bovine Serum Albumin with a Poly(ethylene glycol) Lipid Conjugate. Biomacromolecules 2007; 8:2244-9. [PMID: 17585805 DOI: 10.1021/bm070116o] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, we report the formation of complexes by self-assembly of bovine serum albumin (BSA) with a poly(ethylene glycol) lipid conjugate (PEG2000-PE) in phosphate saline buffer solution (pH 7.4). Three different sets of samples have been studied. The BSA concentration remained fixed (1, 0.01, or 0.001 wt % BSA) within each set of samples, while the PEG2000-PE concentration was varied. Dynamic light scattering (DLS), rheology, and small-angle X-ray scattering (SAXS) were used to study samples with 1 wt % BSA. DLS showed that BSA/PEG2000-PE aggregates have a size intermediate between a BSA monomer and a PEG2000-PE micelle. Rheology suggested that BSA/PEG2000-PE complexes might be surrounded by a relatively compact PEG-lipid shell, while SAXS results showed that depletion forces do not take an important role in the stabilization of the complexes. Samples containing 0.01 wt % BSA were studied by circular dichroism (CD) and ultraviolet fluorescence spectroscopy (UV). UV results showed that at low concentrations of PEG-lipid, PEG2000-PE binds to tryptophan (Trp) groups in BSA, while at high concentrations of PEG-lipid the Trp groups are exposed to water. CD results showed that changes in Trp environment take place with a minimal variation of the BSA secondary structure elements. Finally, samples containing 0.001 wt % BSA were studied by zeta-potential experiments. Results showed that steric interactions might play an important role in the stabilization of the BSA/PEG2000-PE complexes.
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Affiliation(s)
- Valeria Castelletto
- The University of Reading, Department of Chemistry, Whiteknights, Reading, UK.
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Abstract
We have studied the catalytic efficiency of acetylcholinesterase (AChE) in various solutions with ion-disturbed water structure to explore the role that the water structure plays in the substrate-enzyme encounter. The extent of water structuring in the different aqueous solutions was determined by near-infrared spectroscopy. The influence of water structure on the degree of solvation and on the intramolecular mobility of AChE was investigated for different aqueous ionic solutions by small-angle x-ray scattering technique and depolarization fluorescence spectroscopy. It was found that the encounter process between AChE and acetylthiocholine was promoted in solutions with less structured water. In these solutions it was also found that AChE is less solvated coinciding with higher intramolecular mobility. The found experimental results suggest that the water structure may influence the substrate-enzyme encounter process by diminishing the AChE solvation shell and may help diffusion of the substrate through the gorge by enhancing the intramolecular mobility of AChE.
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Affiliation(s)
- Angela S F Ramos
- Max-Planck-Institut für biophysikalische Chemie, Abteilung Spektroskopie und Photochemische Kinetik-Strukturdynamik (bio)chemischer Systeme, 37077 Göttingen, Germany
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