Bio


Experimental and theoretical research is being conducted on a wide range of problems on condensed phase dynamics of small molecules, macromolecules and particles of both materials and biological interest. Work includes development of experimental techniques, thorough experiments on specific systems, and theoretical modeling and computer simulation. Our current work may be conveniently divided into two broad areas:

Structure and Dynamics of Semi-rigid, Rigid and Liquid Crystalline Polymers: Many macromolecules and particles of materials or biological importance may be modeled as rigid or semi-rigid rods. The lab’s objective in this area is to provide an in-depth understanding of the translational, rotational, and flexing dynamics of such materials in liquid dispersions. This work includes studies of local and overall dynamics of rodlike molecules. For example, oligonucleotides and helical polypeptides of varying lengths are being extensively investigated.

The motions of molecules in solutions in which they interact strongly is of great interest in polymer science since most molecules are processed under these conditions. For neutral polymers these interactions occur in the semidilute and concentrated regions. For polyelectrolytes, molecules may interact strongly in low ionic strength solutions at relatively low concentrations because of unshielded electrostatic interactions. Both neutral and charged systems are being studied by theoretical and experimental techniques, including dynamic light scattering, small angle neutron scattering, transient electric birefringence decay and x-ray photon correlation spectroscopy.

Composite Liquids: Composite liquids are a ubiquitous class of materials which contain polymers, particles and solvent. They are used, among other things, as ceramic precursors, lubricants, paints and coatings, adhesives and in chromatographic columns. They are also important constituents of biological systems (e.g., protoplasm, blood). Due to their complexity and the lack of adequate model systems, the interactions between the species in such systems are not well understood. Rod-coil liquids are liquids composed of a rod polymer, a coil polymer and a solvent. Lab members are currently constructing model rod-sphere composite liquids, and model rod/coil/solvent systems which can be studied by scattering techniques.

Academic Appointments


Honors & Awards


  • Fellow, American Association for the Advancement of Science
  • Fellow, American Physical Society
  • Humboldt Senior Scientist Award, Alexander von Humboldt-Foundation (1986)
  • Sloan Foundation Fellow, Alfred P. Sloan Foundation (1967)

Professional Education


  • AB, Columbia University (1959)
  • AM, Columbia University (1960)
  • PhD, Columbia University (1962)

Current Research and Scholarly Interests


The development of the basic principles behind the dynamic light scattering (DLS) technique and its application to a wide variety of liquid systems is one of Pecora's outstanding contributions to physical chemistry. DLS is now an indispensable tool in the repertoire of polymer, colloid and biophysical chemists. It is generally accepted to be one of the best methods for measuring the mutual diffusion coefficients and, in dilute systems, the hydrodynamic sizes of polymers and particulates in solution or suspension. It is widely used, among other things, for studying size distributions of polymer and colloid dispersions; for testing theories of polymer dynamics in dilute and concentrated systems; and for studying interactions between macromolecules and colloidal particles in liquid dispersions. The basic work that established the foundation of this technique was done in the 1960s. Pecora has revisited this area over the years-formulating theories, for instance, of scattering from hollow spheres, large cylindrically symmetric molecules and wormlike chains.

An experimental program began in the early seventies resulted in a now classic series of studies on the rotational dynamics of small molecules in liquids. This work, utilizing mainly depolarized DLS and carbon 13 nuclear magnetic relaxation, has had a wide impact in the area of liquid state dynamics.

It was also during this period that the theoretical foundation for the fluorescence correlation spectroscopy technique (FCS) was formulated. Because of recent advances in equipment and materials, this technique has recently been revived and is now a powerful tool in biophysics.

The experimental and theoretical techniques developed for the study of the dynamics of relatively simple small molecule liquids have been used to investigate more complex systems such as the rotation of small molecule solvents in glassy and amorphous polymers. The resonance- enhanced depolarized light scattering technique was also developed in this period.

Extensive studies using depolarized dynamic light scattering (using the Fabry-Perot interferometer) as well as photon correlation spectroscopy, NMR, FCS and small angle X-ray scattering to the dynamics of oligonucleotides have determined the hydrodynamic diameter of DNA and the internal bending angles of the bases. They also provided support for relations relating hydrodynamic parameters to molecular dimensions for short rodlike molecules and “polyelectrolyte effects” on the translational and rotational motions of these highly charged molecules.

A major area of experimental and theoretical study has been the study of the dynamics of rigid and semirigid rodlike polymers in both dilute and semidilute dispersions. The work on translation and rotation of poly (-benzyl-L-glutamate) in semidilute solution is a foremost early work in this area.

The Pecora group has synthesized and studied the dynamics of model
rigid rod/sphere composite liquids. Studies of the translation of dilute spheres through solutions of the rods as functions of the rod and sphere sizes and the rod concentrations have provided the stimulus for more experiment and theoretical work in this area. Transient electric birefringence decay studies of the rotation of dilute rigid rod polymers in suspensions of comparably sized spherical particles have revealed scaling laws for the rod rotation.

A unique feature of part of this work on rigid and semirigid rodlike polymers is the utilization of genetic engineering techniques to construct a monodisperse, homologous series of DNA restriction fragments. These biologically-produced fragments have served as well-characterized model macromolecules for solution studies of the dynamics of semirigid rodlike polymers.

The well-regarded book of Pecora and Berne on dynamic light scattering, first published in 1976, has become a major reference work. It is now a Dover paperback.

2017-18 Courses


All Publications


  • Diffusion and microstructural properties of solutions of charged nanosized proteins: Experiment versus theory JOURNAL OF CHEMICAL PHYSICS Gapinski, J., Wilk, A., Patkowski, A., Haussler, W., Banchio, A. J., Pecora, R., Nagele, G. 2005; 123 (5)

    Abstract

    We have reanalyzed our former static small-angle x-ray scattering and photon correlation spectroscopy results on dense solutions of charged spherical apoferritin proteins using theories recently developed for studies of colloids. The static structure factors S(q), and the small-wave-number collective diffusion coefficient D(c) determined from those experiments are interpreted now in terms of a theoretical scheme based on a Derjaguin-Landau-Verwey-Overbeek-type continuum model of charged colloidal spheres. This scheme accounts, in an approximate way, for many-body hydrodynamic interactions. Stokesian dynamics computer simulations of the hydrodynamic function have been performed for the first time for dense charge-stabilized dispersions to assess the accuracy of the theoretical scheme. We show that the continuum model allows for a consistent description of all experimental results, and that the effective particle charge is dependent upon the protein concentration relative to the added salt concentration. In addition, we discuss the consequences of small ions dynamics for the collective protein diffusion within the framework of the coupled-mode theory.

    View details for DOI 10.1063/1.1996569

    View details for Web of Science ID 000231168700070

    View details for PubMedID 16108686

  • Dynamics of biological polyelectrolytes 1st French-Brazilian-Polymer Conference (FBPOL-2005) Pecora, R. WILEY-V C H VERLAG GMBH. 2005: 18–23
  • Self-diffusion in solutions of a 20 base pair oligonucleotide: Effects of concentration and ionic strength JOURNAL OF CHEMICAL PHYSICS Wilk, A., Gapinski, J., Patkowski, A., Pecora, R. 2004; 121 (21): 10794-10802

    Abstract

    The long-time self-diffusion coefficients of a 20 base pair duplex oligonucleotide are measured as functions of 20-mer and added NaCl salt concentrations. The self-diffusion coefficients decrease monotonically with increasing 20-mer concentrations for the high-added salt sample and display non-monotonically decreasing 20-mer concentration dependences at lower added salt concentrations. The non-monotonic behavior is attributed to the opposing effects of the tendency to increase the interactions between 20-mers as the concentration is increased and to a decrease in the extent of the Coulomb forces as counterions from the 20-mer increasingly screen them. Attempts to account for the effect of the Coulomb forces on the self-diffusion coefficients by using effective dimensions in the hard rod theory give good agreement with experiment at the highest salt concentration studied. For the lower salt concentrations there appear to be two scaling regimes--one at low polyion concentration in which the high salt scaling of the rod dimensions by adding the Debye screening to the length and diameter of the rod is appropriate and one at high polyion concentrations where the scaling of the dimensions is the addition of 1/2 the Debye screening length. Estimates of the "overlap" concentration C*=1/L(eff) indicate that the non-monotonic decrease occurs at concentrations lower than C*. Finally, the fluorescence correlation spectroscopy self-diffusion coefficients measured here are compared with the mutual diffusion coefficients measured by dynamic light scattering.

    View details for DOI 10.1063/1.1811599

    View details for Web of Science ID 000225136300058

    View details for PubMedID 15549965

  • Translational and rotational dynamics of rodlike cellulose whiskers LANGMUIR Lima, A. M., Wong, J. T., Paillet, M., Borsali, R., Pecora, R. 2003; 19 (1): 24-29

    View details for DOI 10.1021/la020475z

    View details for Web of Science ID 000180332500005

  • Scattering properties of rod-coil and once-broken rod block copolymers MACROMOLECULES Borsali, R., Lecommandoux, S., Pecora, R., Benoit, H. 2001; 34 (12): 4229-4234

    View details for DOI 10.1021/ma001760x

    View details for Web of Science ID 000169049000061

  • Dynamic light scattering and small-angle neutron scattering studies of ternary rod/coil/solvent systems MACROMOLECULES Hanson, E. T., Borsali, R., Pecora, R. 2001; 34 (7): 2208-2219
  • Effect of electrostatic interactions on the dynamics of semiflexible monodisperse DNA fragments JOURNAL OF CHEMICAL PHYSICS Liu, H., Gapinski, J., Skibinska, L., Patkowski, A., Pecora, R. 2000; 113 (14): 6001-6010
  • Dynamic light scattering measurement of nanometer particles in liquids JOURNAL OF NANOPARTICLE RESEARCH Pecora, R. 2000; 2 (2): 123-131
  • Rotational dynamics of rodlike polymers in a rod/sphere mixture JOURNAL OF CHEMICAL PHYSICS Phalakornkul, J. K., Gast, A. P., Pecora, R. 2000; 112 (14): 6487-6494
  • Instrumentation and measurement issues for nanometer particles: Workshop summary JOURNAL OF NANOPARTICLE RESEARCH Pui, D. Y., Brock, J. R., Chen, D., Fissan, H., Frisbie, C. D., Lyman, C. E., Miller, J. C., Mulholland, G. W., Pecora, R., Preining, O., Vo-Dinh, T. 2000; 2 (1): 103-112
  • Rotational and translational dynamics of rodlike polymers: A combined transient electric birefringence and dynamic light scattering study MACROMOLECULES Phalakornkul, J. K., Gast, A. P., Pecora, R. 1999; 32 (9): 3122-3135
  • Effect of electrostatic interactions on the structure and dynamics of a model polyelectrolyte. II. Intermolecular correlations JOURNAL OF CHEMICAL PHYSICS Skibinska, L., Gapinski, J., Liu, H., Patkowski, A., FISCHER, E. W., Pecora, R. 1999; 110 (3): 1794-1800
  • Effect of electrostatic interactions on the structure and dynamics of a model polyelectrolyte. I. Diffusion JOURNAL OF CHEMICAL PHYSICS Liu, H., Skibinska, L., Gapinski, J., Patkowski, A., FISCHER, E. W., Pecora, R. 1998; 109 (17): 7556-7566
  • Dynamic light scattering studies of cholesteric and polymer-stabilized cholesteric liquid crystals PHYSICAL REVIEW E Borsali, R., Schroeder, U. P., Yoon, D. Y., Pecora, R. 1998; 58 (3): R2717-R2720
  • Determination of splay and twist relaxation modes in nematic liquid crystals from dynamic light scattering experiments JOURNAL OF PHYSICAL CHEMISTRY B Borsali, R., Yoon, D. Y., Pecora, R. 1998; 102 (33): 6337-6341
  • Small-angle neutron scattering and dynamic light scattering from a polyelectrolyte solution: DNA MACROMOLECULES Borsali, R., Nguyen, H., Pecora, R. 1998; 31 (5): 1548-1555
  • Depolarized dynamic light scattering from three low molecular weight glass forming liquids: A test of the scattering mechanism JOURNAL OF CHEMICAL PHYSICS Patkowski, A., STEFFEN, W., Nilgens, H., FISCHER, E. W., Pecora, R. 1997; 106 (20): 8401-8408
  • Skeletal muscle myosin subfragment 1 dimers BIOPHYSICAL CHEMISTRY Claire, K., Pecora, R., Highsmith, S. 1997; 65 (1): 85-90

    Abstract

    The rate of translational diffusion of skeletal muscle myosin subfragment 1 (S1) was determined from polarized dynamic light scattering autocorrelation measurements. Diffusion rates were expressed in terms of the hydrodynamic radii Rh. At 20 degrees C, in low ionic strength pH 8 solutions, Rh increased from 4.3 nm to 5.7 nm as [S1] was increased from 1.6 to 72 microM. Including MgATP to maintain S1. MgADP. Pi gave equivalent results. When the light scattering data were analyzed, assuming a monomer-dimer equilibrium, a dissociation constant of 83 microM was obtained. Steady state MgATPase activity measurements were made as a function of [ATP] for S1 in the 0.4-7 microM range, and analyzed assuming Michaelis-Menten kinetics. VMAX did not change, but KM increased about tenfold as [S1] was increased over this range. The light scattering and kinetic data were consistent with S1 aggregation at high [S1].

    View details for Web of Science ID A1997WT65900007

    View details for PubMedID 9130377

  • Translational and rotational dynamics of collagen in dilute solution JOURNAL OF PHYSICAL CHEMISTRY B Claire, K., Pecora, R. 1997; 101 (5): 746-753
  • Structure and short-time dynamics of polydisperse charge-stabilized suspensions PHYSICAL REVIEW E Phalakornkul, J. K., Gast, A. P., Pecora, R., Nagele, G., Ferrante, A., MandlSteininger, B., Klein, R. 1996; 54 (1): 661-675
  • DYNAMICS OF A 2311-BASE-PAIR SUPERHELICAL DNA IN DILUTE AND SEMIDILUTE SOLUTIONS MACROMOLECULES Seils, J., Pecora, R. 1995; 28 (3): 661-673
  • DYNAMICS OF FLEXIBLE COILS IN AN ISOREFRACTIVE ROD/COIL COMPOSITE LIQUID .2. TERNARY SOLUTIONS MACROMOLECULES Cantor, A. S., Pecora, R. 1994; 27 (23): 6817-6833
  • DYNAMIC LIGHT-SCATTERING FROM MONODISPERSE 2311-BASE-PAIR CIRCULAR DNA - IONIC-STRENGTH DEPENDENCE MACROMOLECULES Newman, J., Tracy, J., Pecora, R. 1994; 27 (23): 6808-6811
  • DYNAMICS OF FLEXIBLE COILS IN AN ISOREFRACTIVE ROD/COIL COMPOSITE LIQUID .1. BINARY POLYSTYRENE/SOLVENT SOLUTIONS MACROMOLECULES Cantor, A. S., Pecora, R. 1994; 27 (23): 6812-6816
  • AN INVESTIGATION OF THE MICROSTRUCTURE OF A ROD SPHERE COMPOSITE LIQUID MACROMOLECULES Tracy, M. A., Garcia, J. L., Pecora, R. 1993; 26 (8): 1862-1868
  • DIFFUSION IN ROD SPHERE COMPOSITE LIQUIDS 27th Europhysics Conference on Macromolecular Physics Tracy, M. A., Pecora, R. DR DIETRICH STEINKOPFF VERLAG. 1993: 165–170
  • SYNTHESIS, CHARACTERIZATION, AND DYNAMICS OF A ROD SPHERE COMPOSITE LIQUID MACROMOLECULES Tracy, M. A., Pecora, R. 1992; 25 (1): 337-349
  • DYNAMIC LIGHT-SCATTERING STUDY OF A MONODISPERSE-2311 BASE PAIR CIRCULAR DNA MACROMOLECULES SEILS, J. C., Pecora, R. 1992; 25 (1): 354-362
  • DYNAMIC LIGHT-SCATTERING FROM FLEXIBLE RING MACROMOLECULES MACROMOLECULES SEILS, J. C., Pecora, R. 1992; 25 (1): 350-353
  • DYNAMICS OF RIGID AND SEMIRIGID RODLIKE POLYMERS ANNUAL REVIEW OF PHYSICAL CHEMISTRY Tracy, M. A., Pecora, R. 1992; 43: 525-557
  • DYNAMICS OF LOW-MOLECULAR-WEIGHT DNA FRAGMENTS IN DILUTE AND SEMIDILUTE SOLUTIONS MACROMOLECULES GOINGA, H. T., Pecora, R. 1991; 24 (23): 6128-6138
  • DYNAMICS OF OLIGONUCLEOTIDES AND DNA RESTRICTION FRAGMENTS 637TH MEETING OF THE BIOCHEMICAL SOC Pecora, R. PORTLAND PRESS LTD. 1991: 498–98

    View details for Web of Science ID A1991FQ82100078

    View details for PubMedID 1889660

  • PHOTON-CORRELATION SPECTROSCOPY STUDY OF A 2311-BP RELAXED CIRCULAR DNA APPLICABILITY OF ROUSE-ZIMM AND WORMLIKE CHAIN MODELS 637TH MEETING OF THE BIOCHEMICAL SOC Seils, J., Pecora, R. PORTLAND PRESS LTD. 1991: 511–12

    View details for Web of Science ID A1991FQ82100090

    View details for PubMedID 1889671

  • DNA - A MODEL-COMPOUND FOR SOLUTION STUDIES OF MACROMOLECULES SCIENCE Pecora, R. 1991; 251 (4996): 893-898

    Abstract

    Well-defined, monodisperse, homologous series of oligonucleotides and DNA restriction fragments may now be produced and used as models of rigid and semirigid rodlike molecules in solution. Information from optical experiments on these model systems aids in the formulation and testing of theories of macromolecular dynamics in both dilute and concentrated solution.

    View details for Web of Science ID A1991EY62900034

    View details for PubMedID 2000490

  • ROTATIONAL AND TRANSLATIONAL DIFFUSION OF SHORT RODLIKE MOLECULES IN SOLUTION - OLIGONUCLEOTIDES JOURNAL OF CHEMICAL PHYSICS Eimer, W., Pecora, R. 1991; 94 (3): 2324-2329
  • BROWNIAN DYNAMICS SIMULATIONS OF WORMLIKE CHAINS - DYNAMIC LIGHT-SCATTERING FROM A 2311 BASE PAIR DNA FRAGMENT MACROMOLECULES Allison, S. A., SORLIE, S. S., Pecora, R. 1990; 23 (4): 1110-1118
  • CHARACTERIZATION OF THE OVERALL AND INTERNAL DYNAMICS OF SHORT OLIGONUCLEOTIDES BY DEPOLARIZED DYNAMIC LIGHT-SCATTERING AND NMR RELAXATION MEASUREMENTS BIOCHEMISTRY Eimer, W., Williamson, J. R., Boxer, S. G., Pecora, R. 1990; 29 (3): 799-811

    Abstract

    The dynamics of three synthetic oligonucleotides d(CG)4, d(CG)6, and d(CGCGTTGTTCGCG) of different length and shape were studied in solution by depolarized dynamic light scattering (DDLS) and time-resolved nuclear Overhauser effect cross-relaxation measurements. For cylindrically symmetric molecules the DDLS spectrum is dominated by the rotation of the main symmetry axis of the cylinder. The experimental correlation times describe the rotation of the oligonucleotides under hydrodynamic stick boundary conditions. It is shown that the hydrodynamic theory of Tirado and Garcia de la Torre gives good predictions of the rotational diffusion coefficients of cylindrically symmetric molecules of the small axial ratios studied here. These relations are used to calculate the solution dimensions of the DNA fragments from measured correlation times. The hydrodynamic diameter of the octamer and dodecamer is 20.5 +/- 1.0 A, assuming a rise per base of 3.4 A. The tridecamer, d(CGCGTTGTTCGCG), adopts a hairpin structure with nearly spherical dimensions and a diameter of 23.0 +/- 2.0 A. The DDLS relaxation measurements provide a powerful method for distinguishing between different conformations of the oligonucleotides (e.g., DNA double-helix versus hairpin structure). Furthermore, the rotational correlation times are a very sensitive probe of the length of different fragments. The NMR results reflect the anisotropic motion of the molecules as well as the amount of local internal motion present. The experimental correlation time from NMR is determined by the rotation of both the short and long axes of the oligonucleotide.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1990CK38000030

    View details for PubMedID 2337597

  • A DYNAMIC LIGHT-SCATTERING STUDY OF 4 DNA RESTRICTION FRAGMENTS MACROMOLECULES SORLIE, S. S., Pecora, R. 1990; 23 (2): 487-497
  • PREDICTION OF VELOCITY CROSS-CORRELATION COEFFICIENTS OF BINARY-LIQUID MIXTURES JOURNAL OF PHYSICAL CHEMISTRY Bender, T. M., Pecora, R. 1989; 93 (6): 2614-2620
  • BROWNIAN DYNAMICS SIMULATIONS OF A 3-SUBUNIT AND A 10-SUBUNIT WORM-LIKE CHAIN - COMPARISON OF RESULTS WITH TRUMBELL THEORY AND WITH EXPERIMENTAL RESULTS FROM DNA JOURNAL OF CHEMICAL PHYSICS Lewis, R. J., Allison, S. A., Eden, D., Pecora, R. 1988; 89 (4): 2490-2503
  • ROTATIONAL MOTION OF A HOMOLOGOUS SERIES OF SOLVENT MOLECULES IN AMORPHOUS POLY(METHYL METHACRYLATE) .1. STUDIES OF THE SOLVENTS MACROMOLECULES Park, J. K., Pecora, R., OUANO, A. C. 1988; 21 (6): 1717-1722
  • ROTATIONAL MOTION OF A HOMOLOGOUS SERIES OF SOLVENT MOLECULES IN AMORPHOUS POLY(METHYL METHACRYLATE) .2. STUDIES OF THE MIXTURES MACROMOLECULES Park, J. K., Pecora, R., OUANO, A. C. 1988; 21 (6): 1722-1729
  • A DYNAMIC LIGHT-SCATTERING STUDY OF A 2311 BASE PAIR DNA RESTRICTION FRAGMENT MACROMOLECULES SORLIE, S. S., Pecora, R. 1988; 21 (5): 1437-1449
  • DYNAMIC LIGHT-SCATTERING MEASUREMENTS OF MUTUAL DIFFUSION-COEFFICIENTS OF WATER-RICH 2-BUTOXYETHANOL WATER-SYSTEMS JOURNAL OF PHYSICAL CHEMISTRY Bender, T. M., Pecora, R. 1988; 92 (6): 1675-1677
  • DYNAMICS OF RODLIKE MACROMOLECULES IN NONDILUTE SOLUTIONS - POLY(NORMAL-ALKYL ISOCYANATES) MACROMOLECULES KEEP, G. T., Pecora, R. 1988; 21 (3): 817-829
  • TRANSIENT ELECTRIC BIREFRINGENCE MEASUREMENTS OF THE ROTATIONAL AND INTERNAL MOTIONS OF A 1010 BASE PAIR DNA FRAGMENT - FIELD-STRENGTH AND PULSE LENGTH EFFECTS MACROMOLECULES Lewis, R. J., Pecora, R., Eden, D. 1987; 20 (10): 2579-2587
  • COMPARISON OF PREDICTED ROUSE-ZIMM DYNAMICS WITH OBSERVATIONS FOR A 2311 BASE PAIR DNA FRAGMENT MACROMOLECULES Lewis, R. J., Pecora, R. 1986; 19 (7): 2074-2075
  • A DYNAMIC LIGHT-SCATTERING STUDY OF THE TERT-BUTYL ALCOHOL WATER-SYSTEM JOURNAL OF PHYSICAL CHEMISTRY Bender, T. M., Pecora, R. 1986; 90 (8): 1700-1706
  • TRANSIENT ELECTRIC BIREFRINGENCE MEASUREMENTS OF THE ROTATIONAL AND INTERNAL BENDING MODES IN MONODISPERSE DNA FRAGMENTS MACROMOLECULES Lewis, R. J., Pecora, R., Eden, D. 1986; 19 (1): 134-139
  • ABSOLUTE RAYLEIGH RATIOS OF 4 SOLVENTS AT 488 NM MACROMOLECULES Bender, T. M., Lewis, R. J., Pecora, R. 1986; 19 (1): 244-245
  • RESTRICTED ROTATIONAL DIFFUSION OF A RODLIKE SOLVENT IN A POLYMERIC MATRIX MACROMOLECULES OLIVER, N. H., Pecora, R., OUANO, A. C. 1985; 18 (11): 2208-2215
  • GENERAL-THEORY OF DYNAMIC LIGHT-SCATTERING FROM CYLINDRICALLY SYMMETRIC PARTICLES WITH TRANSLATIONAL-ROTATIONAL COUPLING JOURNAL OF CHEMICAL PHYSICS Aragon, S. R., Pecora, R. 1985; 82 (12): 5346-5353
  • ROTATIONAL AND TRANSLATIONAL MOTION OF SUPERCOILED PLASMIDS IN SOLUTION MACROMOLECULES Lewis, R. J., Huang, J. H., Pecora, R. 1985; 18 (5): 944-948
  • 3 PLASMIDS CONSTRUCTED FOR THE PRODUCTION OF MONODISPERSE SEMI-STIFF DNA SAMPLES MACROMOLECULES Lewis, R. J., Huang, J. H., Pecora, R. 1985; 18 (8): 1530-1534
  • REEVALUATION OF THE DYNAMIC-MODEL FOR ROTATIONAL DIFFUSION OF THIN, RIGID RODS IN SEMIDILUTE SOLUTION MACROMOLECULES KEEP, G. T., Pecora, R. 1985; 18 (6): 1167-1173
  • DYNAMICS OF RODLIKE MACROMOLECULES IN SEMIDILUTE SOLUTIONS JOURNAL OF POLYMER SCIENCE-POLYMER SYMPOSIA Pecora, R. 1985: 83-91
  • DYNAMICS OF WORMLIKE CHAINS MACROMOLECULES Aragon, S. R., Pecora, R. 1985; 18 (10): 1868-1875
  • DYNAMIC LIGHT-SCATTERING-STUDIES OF RODLIKE PARTICLES PURE AND APPLIED CHEMISTRY Pecora, R. 1984; 56 (10): 1391-1395
  • DYNAMIC LIGHT-SCATTERING STUDY OF MICELLES IN A HIGH IONIC-STRENGTH SOLUTION JOURNAL OF PHYSICAL CHEMISTRY Flamberg, A., Pecora, R. 1984; 88 (14): 3026-3033
  • REORIENTATION OF SMALL MOLECULES AND ANIONS IN SOLUTION STUDIED BY RESONANCE ENHANCED DYNAMIC RAYLEIGH-SCATTERING JOURNAL OF CHEMICAL PHYSICS Stanton, S. G., Pecora, R., Hudson, B. S. 1983; 78 (6): 3365-3371
  • RESTRICTED FLEXING OF ONCE-BROKEN RODS MACROMOLECULES Zero, K., Pecora, R. 1982; 15 (4): 1023-1027
  • BENDING MOTIONS AND INTERNAL MOTIONS IN MYOSIN ROD BIOCHEMISTRY Highsmith, S., Wang, C. C., Zero, K., Pecora, R., Jardetzky, O. 1982; 21 (6): 1192-1197

    Abstract

    Depolarized light scattering and high-resolution 1H NMR measurements were made on solutions of light meromyosin (LMM) and myosin rod in 0.6 M KCl-0.010 M pyrophosphate, pH 9.5, at 20 degrees C. The light scattering data indicated LMM is a rigid molecule. Myosin rod is best described as a once-broken rod with domains that can freely diffuse in conical volumes. The maximum angle that the cone surface makes with the myosin rod axis is 128 degrees, indicating the bending motion of the domains is largely unrestrained. NMR data indicated the fraction of the structure that could be in a random-coil configuration was equal and less than 0.04 for both hydrodynamically rigid LMM and bending myosin rod. Thus, the flexible bending of myosin rod appears to not be due to a random-coil structure.

    View details for Web of Science ID A1982NF36600013

    View details for PubMedID 7074075

  • ANISOTROPIC LIGHT-SCATTERING FROM PHOSPHOLIPID-VESICLES JOURNAL OF COLLOID AND INTERFACE SCIENCE Aragon, S. R., Pecora, R. 1982; 89 (1): 170-184
  • USE OF LIGAND PROBES IN LIGHT-SCATTERING .3. PRERESONANCE-ENHANCED DEPOLARIZED RAYLEIGH-SCATTERING OF DIBENZOYLMETHANE AND SELECTED DIORGANOTIN(IV) COMPLEXES INORGANIC CHEMISTRY Nelson, W. H., Howard, W. F., Pecora, R. 1982; 21 (4): 1483-1486
  • ROTATIONAL AND TRANSLATIONAL DIFFUSION IN SEMI-DILUTE SOLUTIONS OF RIGID-ROD MACROMOLECULES MACROMOLECULES ZERO, K. M., Pecora, R. 1982; 15 (1): 87-93
  • RESONANCE ENHANCED DYNAMIC RAYLEIGH-SCATTERING JOURNAL OF CHEMICAL PHYSICS Stanton, S. G., Pecora, R., Hudson, B. S. 1981; 75 (12): 5615-5626
  • SOLUTION DIMENSIONS OF THE GRAMICIDIN DIMER BY DYNAMIC LIGHT-SCATTERING BIOCHEMISTRY Michielsen, S., Pecora, R. 1981; 20 (24): 6994-6997

    Abstract

    Gramicidin is thought to form dimeric helical rods in alcohol solutions. In addition, there is evidence that the rod dimensions change upon addition of potassium ions. The present work reports values for the translational and rotational diffusion coefficients of gramicidin in methanol and 95% ethanol and in these same solvents with added KSCN. Solution dimensions are calculated from the diffusion coefficients. The results suggest that gramicidin exists primarily as dimers in these solutions and that the gramicidin rod does indeed become shorter upon addition of potassium ion. These results are consistent with those obtained from X-ray studies on single crystals grown from alcohol solutions.

    View details for Web of Science ID A1981MS62500033

    View details for PubMedID 6172146

  • DYNAMIC LIGHT-SCATTERING-STUDIES OF RIBONUCLEASE BIOPHYSICAL CHEMISTRY Wang, C. C., Cook, K. H., Pecora, R. 1980; 11 (3-4): 439-442

    Abstract

    Dynamic light scattering has been used to measure the translational diffusion coefficients of bovine pancreatic ribonuclease A as functions of temperature and concentration in the presence of 1 M Guanidine-HCl. Data was collected throughout a temperature range including the folding-unfolding transitions. Evidence of a pretransition "swelling" of the protein was observed. Entropy and enthalpy changes upon unfolding were obtained using a two-state model.

    View details for Web of Science ID A1980KC45700020

    View details for PubMedID 6250652

  • THEORY OF DYNAMIC DEPOLARIZED LIGHT-SCATTERING FROM NONRIGID POLYMER-CHAINS .2. FREELY ROTATING CHAINS JOURNAL OF CHEMICAL PHYSICS Moro, K., Pecora, R. 1980; 72 (9): 4958-4963
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    View details for Web of Science ID A1975W224200007

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  • DEPOLARIZED LIGHT-SCATTERING AND CARBON NUCLEAR-RESONANCE MEASUREMENTS OF ISOTROPIC ROTATIONAL CORRELATION TIME OF MUSCLE CALCIUM-BINDING PROTEIN JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Bauer, D. R., Opella, S. J., Nelson, D. J., Pecora, R. 1975; 97 (9): 2580-2582

    View details for Web of Science ID A1975AA53000067

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    View details for Web of Science ID A1974U158800001

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    View details for Web of Science ID A1972Q366400010

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