Mutual diffusion of crystallin proteins at finite concentrations: A light‐scattering study

Delaye, M.; Gromiec, A.

doi:10.1002/bip.360220413

Cited by 47 publications

(23 citation statements)

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“…Although such data have been published, at least for translational diffusion (see, e.g., the work of Delaye and colleagues (16,18,20)), the comparison has apparently not yet been made. The SDC is inversely proportional to the linear size of the Brownian particle, whereas the rotational correlation time is proportional to its volume.…”

Section: The Impact Of Crowding: Rotational Diffusion Is Less Hinderementioning

confidence: 94%

“…Delaye et al concluded that a-crystallin acts as a good model system for colloids with an effective hardsphere radius that is not dependent on concentration (16,17), with translational self-diffusion coefficients (SDCs) that closely follow the macroscopic viscosity (18). Conversely, another report indicated that a-crystallin does not form a compact sphere at all (17) but has a dynamic quaternary structure (19).…”

Section: Introductionmentioning

confidence: 93%

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NMR-Detected Brownian Dynamics of α B-Crystallin over a Wide Range of Concentrations

Roos

Link

Balbach

et al. 2015

Biophysical Journal

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Knowledge about the global translational and rotational motion of proteins under crowded conditions is highly relevant for understanding the function of proteins in vivo. This holds in particular for human αB-crystallin, which is strongly crowded in vivo and inter alia responsible for preventing cataracts. Quantitative information on translational and rotational diffusion is not readily available, and we here demonstrate an approach that combines pulsed-field-gradient NMR for translational diffusion and proton T1ρ/T2 relaxation-time measurements for rotational diffusion, thus overcoming obstacles encountered in previous studies. The relaxation times measured at variable temperature provide a quantitative measure of the correlation function of protein tumbling, which cannot be approximated by a single exponential, because two components are needed for a minimal and adequate description of the data. We find that at high protein concentrations, rotational diffusion is decoupled from translational diffusion, the latter following the macroscopic viscosity change almost quantitatively, resembling the behavior of spherical colloids. Analysis of data reported in the literature shows that well-packed globular proteins follow a scaling relation between the hydrodynamic radius and the molar mass, Rh ∼ M(1/d), with a fractal dimension of d ∼ 2.5 rather than 3. Despite its oligomeric nature, Rh of αB-crystallin as derived from both NMR methods is found to be fully consistent with this relation.

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Section: The Impact Of Crowding: Rotational Diffusion Is Less Hinderementioning

confidence: 94%

Section: Introductionmentioning

confidence: 93%

NMR-Detected Brownian Dynamics of α B-Crystallin over a Wide Range of Concentrations

Roos

Link

Balbach

et al. 2015

Biophysical Journal

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“…Because of the large change in refractive index at the air-cornea interface in terrestrial species, about 80 percent of total refraction results from the cornea. However in mammals the lens is the only tissue capable of accurately focusing light onto the retina, in a process called accommodation [8], [4]. In addition, there is a gradual increase in the refractive index of the human lens from the cortex (1.38, 73 to 80 percent H2O) to the nucleus (1.41, 68 percent H2O), where there is an enrichment of tightly packed Υ-crystallins (see below).…”

Section: The Lens and Cornea: Transparency And Refractionmentioning

confidence: 99%

Congenital cataracts and their molecular genetics

Hejtmancik¹

2008

Seminars in Cell & Developmental Biology

284

248

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Cataract can be defined as any opacity of the crystalline lens. Congenital cataract is particularly serious because it has the potential for inhibiting visual development, resulting in permanent blindness. Inherited cataracts represent a major contribution to congenital cataracts, especially in developed countries. While cataract represents a common end stage of mutations in a potentially large number of genes acting through varied mechanisms in practice most inherited cataracts have been associated with a subgroup of genes encoding proteins of particular importance for the maintenance of lens transparency and homeostasis. The increasing availability of more detailed information about these proteins and their functions and is making it possible to understand the pathophysiology of cataracts and the biology of the lens in general. Transparency and the LensThe lens transmits light with wavelengths from 390 nm to 1200 nm efficiently, extending well above the limit of visual perception (about 720 nm). Lens transparency results from appropriate architecture of lens cells and tight packing of their proteins, resulting in a constant refractive index over distances approximating the wavelength of light [1], [2]. Ultrastructurally, the lens comprises an anterior layer of organelle rich cuboidal epithelial cells covering a large fiber cell mass making up the bulk of the lens (Fig. 1). Layers of nucleated cortical fiber cells form highly ordered concentric shells around the nonnucleated and essentially organelle-free central fiber cells which make up the lens nucleus. The ends of the more peripheral fiber cells abut in branched anterior and posterior sutures. The cellular architecture and arrangement of the fiber cells and particularly their sutures are critical for light transmission and lens transparency [3]. In addition, the stability and close ordering of lens crystallins, which make up 80−90% of the soluble proteins in the lens, are critical for lens transparency. The high protein content of the lens and especially the lens nucleus, approximately 60% of the wet weight --the highest of any tissue, is particularly important for refraction and focusing of light. Solutions of lens crystallins are highly transparent, and as they are concentrated to levels above 450 mg/ml, light scattering actually decreases [4], [5].Cataracts, which can be defined as lens opacities, have multiple causes, but are often associated with breakdown of the lens microarchitecture [3], [6], possibly including vacuole formation and disarray of lens cells, which can cause large fluctuations in density resulting in light scattering. In addition, light scattering and opacity will occur if there is a significant amount of high molecular weight protein aggregates of approximately 1000 Å or more in size [7], [8]. The short-range ordered packing of the lens crystallins is important in this regard. For transparency, crystallins must exist in a homogeneous phase with significant short-range spatial Publisher's Disclaimer: This is a PDF file of an un...

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“…The transparency and high-refractive index of cells in the lens result from tight packing of their proteins, providing a constant refractive index over distances approximating the wavelength of the transmitted light. 24,25 In fact, as lens proteins are diluted to concentrations below that found in the lens, about 450 mg/ml, light scattering actually increases, 35,36 because dilution decreases the weak interactions between unlike proteins that occur at high concentrations and help to maintain lens transparency. 37,38 Finally, there is a gradual increase in the refractive index of the human lens from 1.38 (73–80% H 2 O) in the cortex to 1.42 (68%H 2 O) in the nucleus, in part due to an enrichment of tightly packed γ-crystallins.…”

Section: Transparencymentioning

confidence: 99%

Overview of the Lens

Hejtmancik

Shiels

2015

Progress in Molecular Biology and Translational Science

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In order to accomplish its function of transmitting and focusing light, the crystalline lens of the vertebrate eye has evolved a unique cellular structure and protein complement. These distinct adaptations have provided a rich source of scientific discovery ranging from biochemistry and genetics to optics and physics. In addition, because of these adaptations, lens cells persist for the lifetime of an organism, providing an excellent model of the aging process. The chapters dealing with the lens will demonstrate how the different aspects of lens biology and biochemistry combine in this singular refractive organ to accomplish its critical role in the visual system.

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Mutual diffusion of crystallin proteins at finite concentrations: A light‐scattering study

Cited by 47 publications

References 40 publications

NMR-Detected Brownian Dynamics of α B-Crystallin over a Wide Range of Concentrations

NMR-Detected Brownian Dynamics of α B-Crystallin over a Wide Range of Concentrations

Congenital cataracts and their molecular genetics

Overview of the Lens

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