Roland May

$Research paper thumbnail of Electrooptic effect for cold neutrons in photorefractive materials$

Electrooptic effect for cold neutrons in photorefractive materials

Applied Physics B: Lasers and Optics, 1999

First experimental evidence for the existence of an electrooptic effect for cold neutrons in 7LiN... more First experimental evidence for the existence of an electrooptic effect for cold neutrons in 7LiNbO3 is reported and discussed. The effect is based on the fact that in certain photorefractive crystals a light-induced space-charge field can be generated which causes a modulation of the density via the inverse piezoelectric effect. From such density structures, induced by the internal electric field, cold neutrons can be diffracted.

Small-Angle Neutron Scattering of Biological Macromolecular Complexes Consisting of Proteins and Nucleic Acids

Physik-Nobelpreis 1994 Strukturuntersuchung mit Neutronen

Physik in unserer Zeit, 1994

ABSTRACT

Von Donuts und Zucker: Mit Neutronen biologische Makromoleküle erforschen

Physik in unserer Zeit, 2003

... ROLAND MAY Energie um, und bildet die Purpurmembran von Organis-men, die den Salinen ihre cha... more

$Research paper thumbnail of Neutron diffraction from thermally fixed gratings in photorefractive lithium niobate crystals$

Neutron diffraction from thermally fixed gratings in photorefractive lithium niobate crystals

by F. Havermeyer and Roland May

PHYSICAL REVIEW B, 1999

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Large-scale preparation of fully deuterated cell components. Ribosomes from Escherichia coli with high biological activity

by Raivo Vilu and Roland May

European Journal of Biochemistry, 1993

Some applications of NMR and of neutron scattering require fully deuterated biological material w... more Some applications of NMR and of neutron scattering require fully deuterated biological material which should be highly active and available in large quantities. These requirements are hardly compatible since full deuteration is achieved easily only if cells are grown in minimal media. This condition used in standard batch fermentation results in both low yields and reduced activities of the biological mass. Here we report a method which combines the apparently incompatible requirements taking advantage of a recent observation according to which the appearance of growth inhibiting extracellular products could be prevented. The method was applied for growing Escherichia coli cells, strain MRE600rif (resistance against high doses of rifampicin is used as selection marker) on partially deuterated media (76% and 84% D,O) with glucose as carbon source and on deuterated acetate and succinate with 100% D,O when full deuteration was to be achieved. The essential point for preserving the log-phase character of the cells is that the cultivation is carried out at substrate limiting conditions thus keeping the growth rate at low levels (for glucose the growth rate, p 5 0.35 h-', for acetatelsuccinate p 5 0.1 h-') which avoids the accumulation of the substrate or of by-products in the medium. Our data suggest that acetate is a main extracellular component for accompanying or triggering the transition from logarithmic growth to stationary phase of E. coli cells cultivated on glucose as carbon source.

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On the transition between a heterogenous and homogenous corona in mixed polymeric micelles

Langmuir, 2008

Two-dimensional NMR and small-angle neutron scattering experiments were performed on comicelles o... more Two-dimensional NMR and small-angle neutron scattering experiments were performed on comicelles of poly(N-methyl-2-vinyl pyridinium iodide)-block-poly(ethylene oxide), P2MVP-b-PEO, and poly(acrylic acid)-block-poly(acryl amide), PAA-b-PAAm, in aqueous solutions to study whether a transition between a heterogeneous (Janus-type) and homogeneous corona can be observed upon a variation of parameters that are anticipated to affect the miscibility of the PEO and PAAm coronal blocks. Investigated

Neutron Small Angle Scattering on Liquid Helium in the temperature Range 1.5-4.2 K

The small angle neutron scattering from liquid helium at saturated vapour pressure in the tempera... more The small angle neutron scattering from liquid helium at saturated vapour pressure in the temperature range from 1.5 to 4.2 K was measured with the instrument D22 of the ILL Grenoble at a wavelength of 4.6 angstrom. The zero angle cross section is monotonically decreasing with decreasing temperature and does not show any singularity at the lambda-point. On the other handd, we observe a change of the slope of the temperature dependence of thw second momentum of the pair correlation function at the lambda-point that reflects the transition of liquid to the superfluid state.

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Double superhelix model of high density lipoprotein

The Journal of Biological Chemistry, Oct 1, 2009

High density lipoprotein (HDL), the carrier of socalled "good" cholesterol, serves as the major a... more High density lipoprotein (HDL), the carrier of socalled "good" cholesterol, serves as the major athero-protective lipoprotein and has emerged as a key therapeutic target for cardiovascular disease. We applied small angle neutron scattering (SANS) with contrast variation and selective isotopic deuteration to the study of nascent HDL to obtain the low resolution structure in solution of the overall time-averaged conformation of apolipoprotein A1 (apoA1) versus the lipid (acyl chain) core of the particle. Remarkably, apoA1 is observed to possess an open helical shape that wraps around a central ellipsoidal lipid phase. Using the low resolution SANS shapes of the protein and lipid core as scaffolding, an all-atom computational model for the protein and lipid components of nascent HDL was developed by integrating complementary structural data from hydrogen deuterium exchange mass spectrometry and previously published constraints from multiple biophysical techniques. Both SANS data and the new computational model, the Double Super Helix model, suggest an unexpected structural arrangement of protein and lipids of nascent HDL, an anti-parallel double super helix wrapped around an ellipsoidal lipid phase. The protein and lipid organization in nascent HDL envisages a potential generalized mechanism for lipoprotein biogenesis and remodeling, biological processes critical to sterol and lipid transport, organismal energy metabolism, and innate immunity. http://www.jbc.org/cgi/

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Structural Changes of the Escherichia coliGroEL–GroES Chaperonins upon Complex Formation in Solution: A Neutron Small Angle Scattering Study

J Struct Biol, 1998

We applied neutron scattering in conjunction with deuterium (D-) labeling in order to obtain info... more We applied neutron scattering in conjunction with deuterium (D-) labeling in order to obtain information about the domain structure of GroEL and GroES isolated and in the complex. Each subunit of the heptameric GroES consists of two domains, a core domain (Met1 to Lys15 and Lys34 to Ala97) and an intervening loop region (Glu16 to Ala33). Neutron scattering shows that both regions change their conformation upon GroEL/GroES complex formation. The interdomain angle between the core regions of the heptameric GroES increases from 120 to 140 degrees, leading to a less dome-like shape of GroES, and the loop regions turn inwards by 75 degrees. The 23 C-terminal amino acids of the 14 GroEL subunits (Lys526 to Met548), which are unresolved in the crystal structure, are located either at the bottom of the cavity formed by the seven-membered GroEL ring or at the inner wall of the cavity. Upon complex formation the apical domains of GroEL move outwards, which facilitates binding of GroES at a Gro-EL-GroES center-to-center distance of (87 +/- 8) A. These structural changes may be important for the dissociation of the unfolded protein bound to the central cavity upon GroES binding. The overall structure determined by neutron scattering in solution tallies with the crystallographic model published after completion of this study. Differences in the conformation of GroES observed in the complex by the two methods support the view that the chaperonin complex is a flexible molecule which might switch in solution between different conformations.

The electro-neutron-optic coefficient of LiNbO3

Page 1. p. 1 The electro-neutron-optic coefficient of LiNbO3 Romano A. Rupp and Martin Fally Inst... more

Mechanism of formation of DNA-cationic vesicle complexes

Faraday Discussions, 2003

Cationic vesicles and DNA form complexes that are promising gene delivery systems. Despite the in... more Cationic vesicles and DNA form complexes that are promising gene delivery systems. Despite the increasing number of publications on their morphology and structure, the mechanism leading to their formation is not yet understood due to a lack of kinetic data. In the present study the kinetics of the interaction between DNA and cationic vesicles were followed using stopped-flow turbidity and small-angle neutron scattering techniques. The neutron real-time experiments were performed on a high-flux diffractometer, the D22 at the ILL, using a stopped-flow set-up. Extruded mixed vesicles of dimethyldioctadecylammonium bromide (DODAB) with various amounts of dioleoylphosphatidylethanolamine (DOPE) were investigated at 25 degrees C. The results show that the transition from unilamellar vesicles to a multilamellar structure upon DNA addition occurs in three steps. The first step, on the millisecond time scale, is currently not accessible to neutron scattering but was observed by stopped-flow turbidity and fluorescence experiments. The second step, on a time scale of seconds, corresponds to the formation of an intermediate with a locally cylindrical structure. As time progresses this unstable intermediate evolves to a multilamellar structure, on a time scale of minutes. An understanding of the mechanisms behind the DNA-cationic vesicle complex formation event will allow the production of more homogeneous, efficient delivery systems in pharmaceutically acceptable forms.

Neutron scattering measurements with the label triangulation method on the 50 S subunit of E. coli ribosomes

Brookhaven symposia in biology

In the E. coli 50 S ribosomal subunit, proteins L7/L12 and L10 were deuterated by partial reconst... more

Label Triangulation

Structural elements of the 50 S subunit of E. coli ribosomes

Basic life sciences

The large (50 S) subunit from E. coli ribosomes consists of 32 different proteins and two RNA mol... more The large (50 S) subunit from E. coli ribosomes consists of 32 different proteins and two RNA molecules of different length. In an attempt to determine the three-dimensional arrangement of the proteins in the subunit, we are also interested in obtaining direct information on the shape of the proteins within the subunit. This is possible only with ribosomal subunits which, unlike natural protonated subunits, are homogeneous for neutrons. These homogeneous particles are produced by reconstituting 50 S particles from RNA and proteins isolated from bacteria grown at different levels of D2O in the culture medium, 76% D2O for RNA and 84% D2O for proteins. Model calculations and test experiments reveal that the pursued strategy allows direct determination of radii of gyration of 50 S components within the particle with reasonable precision. Data evaluation and interpretation are significantly facilitated by contrast variation of the reconstituted particles. The determination of protein shape parameters is only one aspect of the new strategy. The pair distance measurements are completely independent of its success. Data on radii of gyration of five ribosomal proteins in situ are reported: L1 (26 +/- 2 A), L2 (22 +/- 2 A), L3 (22 +/- 2 A), L4 (20 +/- 2 A), and L23 (13 +/- 2 A).

Hyperacetylation of Core Histones Does Not Cause Unfolding of Nucleosomes

Recent studies report that the frictional resistance of partially acetylated core particles incre... more Recent studies report that the frictional resistance of partially acetylated core particles increases when the number of acetyl groups/particle exceeds 10 (Bode, J., Gomez-Lira, M. M. &amp; Schröter, H. (1983) Eur. J. Biochem. 130, 437-445). This was attributed to an opening of the core particle though other explanations, e.g. unwinding of the DNA ends were also suggested. Another possible explanation is that release of the core histone N-terminal domains by acetylation increased the frictional resistance of the particle. Neutron scatter studies have been performed on core particles acetylated to different levels up to 2.4 acetates/H4 molecule. Up to this level of acetylation the neutron scatter data show no evidence for unfolding of the core particle. The fundamental scatter functions for the envelope shape and internal structure are identical to those obtained previously for bulk core particles. The structure that gave the best fit to these fundamental scatter functions was a flat disc of diameter 11-11.5 nm and of thickness 5.5-6 nm with 1.7 +/- 0.2 turns of DNA coiled with a pitch of 3.0 nm around a core of the histone octamer. The data analysis emphasizes the changes in pair distance distribution functions at relatively low contrasts, particularly when the protein is contrast matched and DNA dominates the scatter. Under these conditions there is no evidence for the unwinding of long DNA ends in the hyperacetylated core particles. The distance distribution functions go to zero between 11.5 and 12 nm which gives the maximum chord length in a particle of dimension, 11 nm X 5.5 nm. The distance distribution function for the histone octamer contains 85% of the vectors within the 7.0-nm diameter of the histone core. 15% of the histone vectors lie between 7.0 and 12.0 nm, and these are attributed to the N-terminal domains of the core histones which extend out from the central histone core. Histone vectors extending beyond 7.0 nm are necessary to account for the measured radius of gyration of the histone core of 3.3 nm. A similar value of 3.2 nm is calculated for the recent ellipsoidal shape of 11.0 X 6.5 X 6.5 nm from the crystal structure of the octamer. However, the nucleosome model based on this structure is globular, roughly 11 nm in diameter, which does not accord with the flat disc shape core particle obtained from detailed neutron scatter data nor with the cross-section radii of gyration of the histone and DNA found previously for extended chromatin in solution.

Structure Factor Distortions for Hard-sphere Dispersions Subjected to Weak Shear Flow: Small Angle Neutron Scattering in the Flow-Vorticity Plane

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Hyperacetylation of core histones does not cause unfolding of nucleosomes. Neutron scatter data accords with disc shape of the nucleosome

Journal of Biological Chemistry

Recent studies report that the frictional resistance of partially acetylated core particles incre... more Recent studies report that the frictional resistance of partially acetylated core particles increases when the number of acetyl groups/particle exceeds 10 (Bode, J., Gomez-Lira, M. M. &amp; Schröter, H. (1983) Eur. J. Biochem. 130, 437-445). This was attributed to an opening of the core particle though other explanations, e.g. unwinding of the DNA ends were also suggested. Another possible explanation is that release of the core histone N-terminal domains by acetylation increased the frictional resistance of the particle. Neutron scatter studies have been performed on core particles acetylated to different levels up to 2.4 acetates/H4 molecule. Up to this level of acetylation the neutron scatter data show no evidence for unfolding of the core particle. The fundamental scatter functions for the envelope shape and internal structure are identical to those obtained previously for bulk core particles. The structure that gave the best fit to these fundamental scatter functions was a flat disc of diameter 11-11.5 nm and of thickness 5.5-6 nm with 1.7 +/- 0.2 turns of DNA coiled with a pitch of 3.0 nm around a core of the histone octamer. The data analysis emphasizes the changes in pair distance distribution functions at relatively low contrasts, particularly when the protein is contrast matched and DNA dominates the scatter. Under these conditions there is no evidence for the unwinding of long DNA ends in the hyperacetylated core particles. The distance distribution functions go to zero between 11.5 and 12 nm which gives the maximum chord length in a particle of dimension, 11 nm X 5.5 nm. The distance distribution function for the histone octamer contains 85% of the vectors within the 7.0-nm diameter of the histone core. 15% of the histone vectors lie between 7.0 and 12.0 nm, and these are attributed to the N-terminal domains of the core histones which extend out from the central histone core. Histone vectors extending beyond 7.0 nm are necessary to account for the measured radius of gyration of the histone core of 3.3 nm. A similar value of 3.2 nm is calculated for the recent ellipsoidal shape of 11.0 X 6.5 X 6.5 nm from the crystal structure of the octamer. However, the nucleosome model based on this structure is globular, roughly 11 nm in diameter, which does not accord with the flat disc shape core particle obtained from detailed neutron scatter data nor with the cross-section radii of gyration of the histone and DNA found previously for extended chromatin in solution.

Neutron-Scattering Analysis of Structural and Functional Aspects of the Ribosome: The Strategy of the Glassy Ribosome

Protein-decorated micelle structure of sodium-dodecyl-sulfate--protein complexes as determined by neutron scattering

European Journal of Biochemistry

The structure of the complex between sodium dodecyl sulfate (SDS) and a deuterated bifunctional e... more The structure of the complex between sodium dodecyl sulfate (SDS) and a deuterated bifunctional enzyme, N-5'-phosphoribosylanthranilate isomerase/indole-3-glycerol-phosphate synthase (Mr 49 484), has been studied in dilute solution by small-angle neutron scattering. The complex nearly acquired its final size, as shown by molecularsieve chromatography, at the chosen SDS concentration of 1.6 mM, which is slightly below the critical micelle concentration of 1.8 mM (at the ionic strength of 0.1 M). The 452 amino-acid residues of the bifunctional enzyme were combined with 216 detergent molecules. The complex was found to be composed of three protein-decorated SDS micelles of unequal size, connected by short flexible polypeptide segments. The largest of the three micelles was the middle one. The SDS-protein complex contained the dodecyl hydrocarbon moieties in three globular cores. Each core was surrounded by a hydrophilic shell, formed by the hydrophilic and amphiphilic stretches of the polypeptide chain, and by the sulfate head groups of the detergent. The average thickness of these shells was 0.7-0.8 nm.

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