Structure of a short-lived excited state trinuclear Ag–Pt–Pt complex in aqueous solution by time resolved X-ray scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

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Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181269 ◽

1990 ◽

Vol 48 (1) ◽

pp. 502-503

Author(s):

Eva-Maria Mandelkow ◽

Ron Milligan

Keyword(s):

Electron Microscopy ◽

Dynamic Instability ◽

Entire Solution ◽

Reaction Scheme ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

A Chain ◽

Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

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In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

10.26434/chemrxiv.9876395.v1 ◽

2019 ◽

Author(s):

Hao Wu ◽

Jeffrey Ting ◽

Siqi Meng ◽

Matthew Tirrell

Keyword(s):

Small Angle ◽

Self Assembly ◽

Electrostatic Interactions ◽

Polyelectrolyte Complex ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Kinetics Of ◽

Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

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Faculty Opinions recommendation of Time-resolved small-angle X-ray scattering investigation of the folding dynamics of heme oxygenase: implication of the scaling relationship for the submillisecond intermediates of protein folding.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1007608.373952 ◽

2006 ◽

Author(s):

Kunihiro Kuwajima

Keyword(s):

Protein Folding ◽

Heme Oxygenase ◽

Small Angle ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Scaling Relationship ◽

Folding Dynamics ◽

Ray Scattering

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Time-Resolved, in Situ, Small- and Wide-Angle X-ray Scattering To Monitor Pt Nanoparticle Structure Evolution Stabilized by Adsorbed SnCl3– Ligands During Synthesis

The Journal of Physical Chemistry C ◽

10.1021/jp4015788 ◽

2013 ◽

Vol 117 (15) ◽

pp. 7924-7933 ◽

Cited By ~ 13

Author(s):

Samuel St. John ◽

Naiping Hu ◽

Dale W. Schaefer ◽

Anastasios P. Angelopoulos

Keyword(s):

Structure Evolution ◽

Wide Angle ◽

Pt Nanoparticle ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Nanoparticle Structure ◽

Ray Scattering

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Arguments for an additional long-lived intermediate in the photocycle of the full-length aureochrome 1c receptor: A time-resolved small-angle X-ray scattering study

Structural Dynamics ◽

10.1063/1.5095063 ◽

2019 ◽

Vol 6 (3) ◽

pp. 034701 ◽

Cited By ~ 1

Author(s):

Saskia Bannister ◽

Elena Böhm ◽

Thomas Zinn ◽

Thomas Hellweg ◽

Tilman Kottke

Keyword(s):

Small Angle ◽

Full Length ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Scattering Study ◽

Ray Scattering

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A Small-Angle X-Ray Scattering Study on Pre-Irradiated Malate Synthase. The Influence of Formate, Superoxide Dismutase, and Catalase on the X-Ray Induced Aggregation of the Enzyme

Zeitschrift für Naturforschung C ◽

10.1515/znc-1985-5-614 ◽

1985 ◽

Vol 40 (5-6) ◽

pp. 364-372 ◽

Cited By ~ 7

Author(s):

P. Zipper ◽

R. Wilfing ◽

M. Kriechbaum ◽

H. Durchschlag

Keyword(s):

Aqueous Solution ◽

Superoxide Dismutase ◽

Small Angle ◽

Malate Synthase ◽

X Ray ◽

X Ray Scattering ◽

X Irradiation ◽

The Mean ◽

Induced Aggregation ◽

Ray Scattering

Abstract The sulfhydryl enzyme malate synthase from baker’s yeast was X-irradiated with 6 kGy in air-saturated aqueous solution (enzyme concentration: ≃ 10 mg/ml; volume: 120 μl), in the absence or presence of the specific scavengers formate, superoxide dismutase, and catalase. After X-irradiation, a small aliquot of the irradiated solutions was tested for enzymic activity while the main portion was investigated by means of small-angle X-ray scattering. Additionally, an unirradiated sample without additives was investigated as a reference. Experiments yielded the following results: 1. X-irradiation in the absence of the mentioned scavengers caused considerable aggregation, fragmentation, and inactivation of the enzyme. The dose Dt37 for total (= repairable + non-repayable) inactivation resulted as 4.4 kGy. The mean radius of gyration was found to be about 13 nm. The mean degree of aggregation was obtained as 5.7, without correction for fragmentation. An estimation based on the thickness factor revealed that about 19% of material might be strongly fragmented. When this amount of fragments was accordingly taken into account, a value of 7.1 was obtained as an upper limit for the mean degree of aggregation. The observed retention of the thickness factor and the finding of two different cross-section factors are in full accord with the two-dimensional aggregation model established previously (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99 - 121 (1980)). 2. The presence of catalytic amounts of superoxide dismutase and/or catalase, in the absence of formate, during X-irradiation reduced both aggregation and inactivation significantly. 3. The presence of formate (10 or 100 mᴍ) during X-irradiation led to a strong decrease of aggregation and inactivation. This effect was more pronounced with the higher formate concentration or when superoxide dismutase and/or catalase were simultaneously present during X-irradiation. The presence of formate also reduced the amount of fragments significantly. 4. The results clearly show that the aggregation and inactivation of malate synthase upon X-irradiation in aqueous solution are mainly caused by OH·; to a minor extent O·̄2 and H2O2 are additionally involved in the damaging processes.

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