1
|
Wang WL, Min Y, Yu SS, Chen W, Chen JJ, Liu XY, Yu HQ. Probing electron transfer between hemin and riboflavin using a combination of analytical approaches and theoretical calculations. Phys Chem Chem Phys 2017; 19:32580-32588. [DOI: 10.1039/c7cp06492f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proton-coupled electron transfer mechanisms of riboflavin bound hemin in aqueous solution are elucidated by spectroelectrochemical analysis, the electron paramagnetic resonance method and theoretical calculations.
Collapse
Affiliation(s)
- Wen-Lan Wang
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Yuan Min
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Sheng-Song Yu
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Wei Chen
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Jie-Jie Chen
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Xiao-Yang Liu
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| |
Collapse
|
2
|
Liebisch P, Dau H. Linear Dichroism in the XANES of Partially Oriented Samples: Theory and Application to the Photosynthetic Manganese Complex. Chemphyschem 2010; 11:1236-47. [DOI: 10.1002/cphc.200900954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
3
|
Krishnan V, Strzalka J, Liu J, Liu C, Kuzmenko I, Gog T, Blasie JK. Interferometric enhancement of x-ray reflectivity from unperturbed Langmuir monolayers of amphiphiles at the liquid-gas interface. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:021604. [PMID: 20365571 DOI: 10.1103/physreve.81.021604] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 11/24/2009] [Indexed: 05/29/2023]
Abstract
Langmuir monolayers provide an important system for the investigation of the intramolecular structure and intermolecular ordering of organic and bio-organic macromolecular amphiphiles at an interface between polar and nonpolar media, e.g., the liquid-gas interface. Specular x-ray and neutron reflectivity have contributed substantially to these investigations. However, these reflectivity techniques are generally limited by the absence of crucial phase information, the relatively small contribution of the amphiphile to the scattering-length density contrast across the interface, and the relatively limited range of momentum transfer available perpendicular to the interface. Although several procedures have been developed to provide model-independent solutions to the phase problem, there remains a limited ability to distinguish features of slightly differing contrast (i.e., the "sensitivity") as well as their minimum allowable separation (i.e., the "spatial resolution") along the length of the scattering-length density profile derived from the reflectivity data via solution to the phase problem. Here, we demonstrate how the well-known interferometric approach can be extended to the structural investigation of otherwise unperturbed Langmuir monolayers of these amphiphiles to provide a direct solution to the phase problem and importantly, substantially enhance both the sensitivity and the spatial resolution in the derived profiles.
Collapse
Affiliation(s)
- Venkata Krishnan
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | | | | | |
Collapse
|
4
|
Trzaskowski B, Leonarski F, Leś A, Adamowicz L. Altering the Orientation of Proteins on Self-Assembled Monolayers: A Computational Study. Biomacromolecules 2008; 9:3239-45. [DOI: 10.1021/bm800806n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bartosz Trzaskowski
- Department of Chemistry, University of Arizona, Tucson, Arizona 85716, and Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Poland
| | - Filip Leonarski
- Department of Chemistry, University of Arizona, Tucson, Arizona 85716, and Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Poland
| | - Andrzej Leś
- Department of Chemistry, University of Arizona, Tucson, Arizona 85716, and Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Poland
| | - Ludwik Adamowicz
- Department of Chemistry, University of Arizona, Tucson, Arizona 85716, and Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Poland
| |
Collapse
|
5
|
Jacobsen K, Risse T. On the origin of the polar order of T4 lysozyme on planar model surfaces. J Phys Chem B 2008; 112:967-72. [PMID: 18171040 DOI: 10.1021/jp075375m] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Site directed spin labeling is used to investigate the origin of the macroscopic alignment of T4 lysozyme vectorially tethered to planar biomimetic surfaces. T4 lysozyme was adsorbed to a quartz-supported dioleoylphosphatidylcholine (DOPC) bilayer by selective binding of the histidine-tagged protein to functionalized headgroups (1,2-dioleoyl-sn-glycero-3-[[N(5-amino-1-carboxypentyl)iminodiacetic acid]succinyl], DOGS NTA) of the bilayer. This results in a polar oriented ensemble of proteins on the surface, which gives rise to angular-dependent electron paramagnetic resonance (EPR) spectra. In order to reveal the mechanism of the protein alignment, the influence of protein coverage on the order of the molecules was addressed. Along the lines described previously for a full monolayer (Jacobsen, et al. Biophys. J. 2005, 88, 4351), the polar orientation of the molecules was inferred from an analysis of the EPR line shape using the stochastic Liouville equation (SLE) approach developed by Freed and co-workers. The simulations reveal that the orientation of the protein is strongly determined by lateral protein-protein interactions. In comparison to the lipid bilayer, a fusion protein of T4 lysozyme (T4L) with Annexin XII was investigated, where the two-dimensional crystallization of Annexin XII on a dioleoylphosphatidylserine (DOPS) bilayer provides a surface layer of regularly anchored T4L molecules. For this system, it is found that the interaction between T4L and Annexin plays a more important role for understanding the structure in the adsorbed state.
Collapse
Affiliation(s)
- Kerstin Jacobsen
- Fritz Haber Institute of Max Planck Society, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany
| | | |
Collapse
|
6
|
Yu Q, Golden G. Probing the protein orientation on charged self-assembled monolayers on gold nanohole arrays by SERS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:8659-62. [PMID: 17629308 DOI: 10.1021/la7007073] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In this work, surface-enhanced Raman scattering (SERS) was applied to probe the orientation of cytochrome c (Cyt-c) on gold nanohole arrays functionalized with self-assembled monolayers (SAMs) of alkane thiols with positively (-NH2) and negatively (-COOH) charged terminal groups. Square grid gold nanohole arrays with a nanohole diameter of 270 nm and a grating of 350 nm were fabricated by electron beam lithography (EBL) and were used as the SERS substrates. The SERS intensities of the nontotally symmetric mode (B(1g) mode nu(11)) and the totally symmetric mode (A(1g) mode nu(4)) and their ratios were used to determine the orientation of Cyt-c on surfaces. The results indicate that the heme group is close and perpendicular to the negatively charged surface but is far from and oriented at an angle to the positively charged surface. Cyt-c has a random or more flat orientation on the bare Au nanoholes surface.
Collapse
Affiliation(s)
- Qiuming Yu
- Department of Chemical Engineering, Center for Nanotechnology, University of Washington, Seattle, Washington 98195, USA.
| | | |
Collapse
|
7
|
Heering HA, Williams KA, de Vries S, Dekker C. Specific vectorial immobilization of oligonucleotide-modified yeast cytochrome C on carbon nanotubes. Chemphyschem 2007; 7:1705-9. [PMID: 16807958 DOI: 10.1002/cphc.200600108] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Iso-1-cytochrome c from the yeast Saccharomyces cerevisiae (YCC) contains a surface cysteine residue, Cys102, that is located opposite to the lysine-rich side containing the exposed heme edge, which is the docking site for enzymes. Site-specific vectorial immobilization of YCC via Cys102 on single-walled carbon nanotubes (SWNT) thus provides a selective interface between nanoscopic electronic devices and complex enzymes. We have achieved this by modification of Cys102 with an oligonucleotide (dT(18)). Atomic force microscopy, fluorescence imaging, and cyclic voltammetry show the specific adsorption of YCC, modified with dT(18), on the SWNT sidewall with retention of its native properties. Pretreatment of the SWNT with Triton-X405 blocks the nonspecific binding of untreated YCC but does not interfere with binding of the oligonucleotide-modified YCC.
Collapse
Affiliation(s)
- Hendrik A Heering
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
| | | | | | | |
Collapse
|
8
|
Xu J, Bowden EF. Determination of the Orientation of Adsorbed Cytochrome c on Carboxyalkanethiol Self-Assembled Monolayers by In Situ Differential Modification. J Am Chem Soc 2006; 128:6813-22. [PMID: 16719461 DOI: 10.1021/ja054219v] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The contact domain utilized by horse cytochrome c when adsorptively bound to a C(10)COOH self-assembled monolayer (SAM) was delineated using a chemical method based on differential modification of surface amino acids. Horse cytochrome c was adsorbed at low ionic strength (pH 7.0, 4.4 mM potassium phosphate) onto 10 microm diameter gold particles coated with HS(CH(2))(10)COOH SAMs. After in situ modification of lysyl groups by reductive Schiff-base methylation, the protein was desorbed, digested using trypsin, and the peptide mapped using LC/MS. Relative lysyl reactivities were ascertained by comparing the resulting peptide frequencies to control samples of solution cytochrome c modified to the same average extent. The least reactive lysines in adsorbed cytochrome c were found to be 13, 72, 73, 79, and 86-88, consistent with a contact region located up and to the left (Met-80 side) of the solvent-exposed heme edge (conventional front face view). The most reactive lysines were 39, 53, 55, and 60, located on the lower backside. The proposed orientation features a heme tilt angle of approximately 35-40 degrees with respect to the substrate surface normal. Factors that can complicate or distort data interpretation are discussed, and the generality of differential modification relative to existing in situ methods for protein orientation determination is also addressed.
Collapse
Affiliation(s)
- Jishou Xu
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA
| | | |
Collapse
|
9
|
Trzaskowski B, Leonarski F, Leś A, Adamowicz L. Modeling Tubulin at Interfaces. Immobilization of Microtubules on Self-Assembled Monolayers. J Phys Chem B 2005; 109:17734-42. [PMID: 16853268 DOI: 10.1021/jp052015v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A theoretical study of protein docking to self-assembled monolayers using a new approach is presented. Docking experiments based on space complementarity implemented in FTDock software were performed for three different proteins: tubulin dimer, cytochrome c, and lysozyme. The proteins were adsorbed on alkanethiol surfaces with different terminating groups and 50,000 best orientations of each protein were analyzed. For all systems three filters based on different chemical and biological approaches were applied. Correctly docked proteins for the cytochrome c and lysozyme systems were found in a list of the first 12 results after applying the geometrical and grouping filter and in a list of the first 3 results after applying the biological filter. We have found that alkanethiol monolayers with odd and even numbers of -CH2- groups have similar properties in terms of interactions with the two proteins. Docking of the tubulin dimer revealed that the orientation favored from the applicational point of view can be found in a list of the first 14 results for monolayers with different terminating groups and that there may be a noticeable difference in tubulin dimer interactions with alkanethiol chains of various length. The results for tubulin dimer docking combined with microtubules ability of reversible assembly suggest that these biological structures may become good candidates to serve as templates for fabrication of nanowires and other nanoscale electronic devices. The new method of theoretical docking presented may be used as a fast and reliable tool complementing other theoretical and experimental techniques of exploring other protein-surface interfaces.
Collapse
|
10
|
Heering HA, Wiertz FGM, Dekker C, de Vries S. Direct Immobilization of Native Yeast Iso-1 Cytochrome c on Bare Gold: Fast Electron Relay to Redox Enzymes and Zeptomole Protein-Film Voltammetry. J Am Chem Soc 2004; 126:11103-12. [PMID: 15339197 DOI: 10.1021/ja046737w] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclic voltammetry shows that yeast iso-1-cytochrome c (YCC), chemisorbed on a bare gold electrode via Cys102, exhibits fast, reversible interfacial electron transfer (k(0) = 1.8 x 10(3) s(-1)) and retains its native functionality. Vectorially immobilized YCC relays electrons to yeast cytochrome c peroxidase, and to both cytochrome cd(1) nitrite reductase (NIR) and nitric oxide reductase from Paracoccus denitrificans, thereby revealing the mechanistic properties of these enzymes. On a microelectrode, we measured nitrite turnover by approximately 80 zmol (49 000 molecules) of NIR, coadsorbed on 0.65 amol (390 000 molecules) of YCC.
Collapse
Affiliation(s)
- Hendrik A Heering
- Contribution from the Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
| | | | | | | |
Collapse
|
11
|
Zhou J, Zheng J, Jiang S. Molecular Simulation Studies of the Orientation and Conformation of Cytochrome c Adsorbed on Self-Assembled Monolayers. J Phys Chem B 2004. [DOI: 10.1021/jp038048x] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Jian Zhou
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195
| | - Jie Zheng
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195
| | - Shaoyi Jiang
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195
| |
Collapse
|
12
|
Nordgren CE, Tobias DJ, Klein ML, Blasie JK. Molecular dynamics simulations of a hydrated protein vectorially oriented on polar and nonpolar soft surfaces. Biophys J 2002; 83:2906-17. [PMID: 12496067 PMCID: PMC1302375 DOI: 10.1016/s0006-3495(02)75300-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
We present a collection of molecular dynamics computer simulation studies on a model protein-membrane system, namely a cytochrome c monolayer attached to an organic self-assembled monolayer (SAM). Modifications of the system are explored, including the polarity of the SAM endgroups, the amount of water present for hydration, and the coordination number of the heme iron atom. Various structural parameters are measured, e.g., the protein radius of gyration and eccentricity, the deviation of the protein backbone from the x-ray crystal structure, the orientation of the protein relative to the SAM surface, and the profile structures of the SAM, protein, and water. The polar SAM appears to interact more strongly with the protein than does the nonpolar SAM. Increased hydration of the system tends to reduce the effects of other parameters. The choice of iron coordination model has a significant effect on the protein structure and the heme orientation. The overall protein structure is largely conserved, except at each end of the sequence and in one loop region. The SAM structure is only perturbed in the region of its direct contact with the protein. Our calculations are in reasonably good agreement with experimental measurements (polarized optical absorption/emission spectroscopy, x-ray interferometry, and neutron interferometry).
Collapse
Affiliation(s)
- C E Nordgren
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
| | | | | | | |
Collapse
|
13
|
Ahluwalia A, De Rossi D, Giusto G, Chen O, Papper V, Likhtenshtein GI. A fluorescent-photochrome method for the quantitative characterization of solid phase antibody orientation. Anal Biochem 2002; 305:121-34. [PMID: 12054440 DOI: 10.1006/abio.2002.5601] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A fluorescent-photochrome method of quantifying the orientation and surface density of solid phase antibodies is described. The method is based on measurements of quenching and rates of cis-trans photoisomerization and photodestruction of a stilbene-labeled hapten by a quencher in solution. These experimental parameters enable a quantitative description of the order of binding sites of antibodies immobilized on a surface and can be used to characterize the microviscosity and steric hindrance in the vicinity of the binding site. Furthermore, a theoretical method for the determination of the depth of immersion of the fluorescent label in a two-phase system was developed. The model exploits the concept of dynamic interactions and is based on the empirical dependence of parameters of static exchange interactions on distances between exchangeable centers. In the present work, anti-dinitrophenyl (DNP) antibodies and stilbene-labeled DNP were used to investigate three different protein immobilization methods: physical adsorption, covalent binding, and the Langmuir-Blodgett technique.
Collapse
Affiliation(s)
- Arti Ahluwalia
- Interdepartmental Research Center "E. Piaggio", via Diotisalvi 2, Pisa, 56126, Italy
| | | | | | | | | | | |
Collapse
|
14
|
Tronin A, Edwards AM, Wright WW, Vanderkooi JM, Blasie JK. Orientation distributions for cytochrome c on polar and nonpolar interfaces by total internal reflection fluorescence. Biophys J 2002; 82:996-1003. [PMID: 11806939 PMCID: PMC1301906 DOI: 10.1016/s0006-3495(02)75459-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The formation of chemisorbed monolayers of yeast cytochrome c on both uncharged polar and nonpolar soft surfaces of organic self-assembled monolayers (SAM) on solid inorganic substrates was followed in situ by polarized total internal reflection fluorescence. Two types of nonpolar surfaces and one type of uncharged polar surface were used. The first type of nonpolar surface contained only thiol endgroups, while the other was composed of a mixture of thiol and methyl endgroups. The uncharged polar surface was provided by the mixture of thiol and hydroxyl endgroups. The thiol endgroups were used to form a covalent disulfide bond with the unique surface-exposed cysteine residue 102 of the protein. The mean tilt angle of the protein's zinc-substituted porphyrin was found to be 41 degrees and 50 degrees for the adsorption onto the nonpolar and uncharged polar surfaces, respectively. The distribution widths for the pure thiol and the thiol/methyl and thiol/hydroxyl mixtures were 9 degrees, 1 degrees, and 18 degrees, respectively. The high degree of the orientational order and good stability achieved for the protein monolayer on the mixed thiol/methyl endgroup SAM makes this system very attractive for studies of both intramolecular and intermolecular electron transfer processes.
Collapse
Affiliation(s)
- Andrey Tronin
- Chemistry Department, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
| | | | | | | | | |
Collapse
|
15
|
Surface-sensitive X-ray and neutron scattering characterization of planar lipid model membranes and lipid/peptide interactions. PEPTIDE-LIPID INTERACTIONS 2002. [DOI: 10.1016/s1063-5823(02)52007-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
16
|
Haas AS, Pilloud DL, Reddy KS, Babcock GT, Moser CC, Blasie JK, Dutton PL. Cytochrome c and Cytochrome c Oxidase: Monolayer Assemblies and Catalysis. J Phys Chem B 2001. [DOI: 10.1021/jp011834m] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alan S. Haas
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, Department of Chemistry, Michigan State University, East Lansing, Michigan, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Denis L. Pilloud
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, Department of Chemistry, Michigan State University, East Lansing, Michigan, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Konda S. Reddy
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, Department of Chemistry, Michigan State University, East Lansing, Michigan, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Gerald T. Babcock
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, Department of Chemistry, Michigan State University, East Lansing, Michigan, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Christopher C. Moser
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, Department of Chemistry, Michigan State University, East Lansing, Michigan, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - J. Kent Blasie
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, Department of Chemistry, Michigan State University, East Lansing, Michigan, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - P. Leslie Dutton
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, Department of Chemistry, Michigan State University, East Lansing, Michigan, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| |
Collapse
|