Using Light Scattering to Determine the Stoichiometry of Protein Complexes

2015 ◽  
pp. 233-238 ◽  
Author(s):  
Jeremy Mogridge
Keyword(s):  
Light Scattering ◽  
Protein Complexes

Structural Insights into Thermotoga maritima FtsH Periplasmic Domain on Substrate Recognition

2016 ◽  
Author(s):  
Jun Yop An ◽  
Humayun Sharif ◽  
Gil Bu Kang ◽  
Kyung Jin Park ◽  
Jung-Gyu Lee ◽  
...  
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Protein Complexes ◽  
Thermotoga Maritima ◽  
Substrate Recognition ◽  
Hydrophobic Membrane ◽  
Membrane Protein Complexes ◽  
Periplasmic Domain ◽  
Ph Dependent ◽  
Structural Insights

Prompt removal of misfolded membrane proteins and misassembled membrane protein complexes is essential for membrane homeostasis. However, the elimination of these toxic proteins from the hydrophobic membrane environment has high energetic barriers. Transmembrane FtsH is the only known ATP-dependent protease responsible for this task, unlike other well-studied soluble ATP-dependent proteases. The mechanisms by which FtsH recognizes, unfolds, translocates, and proteolyzes its substrates remain unclear. Here, we report the crystal structures of the Thermotoga maritima FtsH periplasmic domain (PD) in an associative trimeric state at a 1.5-1.95 Å resolution. We also describe the pH-dependent oligomerization states of the isolated PD using dynamic light scattering. These observations help us understand how FtsH recognizes membrane-anchored misfolded proteins.

Tuning of Silica Nanoparticles-Lysozyme Protein Complexes in presence of SDS Surfactant

Soft Matter ◽  
2021 ◽  
Author(s):  
Debasish Saha ◽  
Sugam Kumar ◽  
Debes Ray ◽  
Jitendra Mata ◽  
Andrew Edward Whitten ◽  
...  
Keyword(s):  
Light Scattering ◽  
Sodium Dodecyl Sulfate ◽  
Dynamic Light Scattering ◽  
Silica Nanoparticles ◽  
Anionic Surfactant ◽  
Protein Complexes ◽  
Sodium Dodecyl ◽  
Cationic Protein ◽  
Dodecyl Sulfate ◽  
Sds Surfactant

The structure of complexes of anionic silica nanoparticles (size16 nm)-lysozyme (cationic) protein, tuned by the addition of anionic surfactant sodium dodecyl sulfate (SDS), has been investigated by dynamic light scattering...

scholarly journals Detection and isolation of cell-derived microparticles are compromised by protein complexes resulting from shared biophysical parameters

Blood ◽  
2011 ◽  
Vol 117 (4) ◽  
pp. e39-e48 ◽  
Author(s):  
Bence György ◽  
Károly Módos ◽  
Éva Pállinger ◽  
Krisztina Pálóczi ◽  
Mária Pásztói ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Light Scattering ◽  
Clinical Laboratory ◽  
Protein Complexes ◽  
Published Data ◽  
Biophysical Parameters ◽  
Laboratory Assessment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Health And Disease

Abstract Numerous diseases, recently reported to associate with elevated microvesicle/microparticle (MP) counts, have also long been known to be characterized by accelerated immune complex (IC) formation. The goal of this study was to investigate the potential overlap between parameters of protein complexes (eg, ICs or avidin-biotin complexes) and MPs, which might perturb detection and/or isolation of MPs. In this work, after comprehensive characterization of MPs by electron microscopy, atomic force microscopy, dynamic light-scattering analysis, and flow cytometry, for the first time, we drive attention to the fact that protein complexes, especially insoluble ICs, overlap in biophysical properties (size, light scattering, and sedimentation) with MPs. This, in turn, affects MP quantification by flow cytometry and purification by differential centrifugation, especially in diseases in which IC formation is common, including not only autoimmune diseases, but also hematologic disorders, infections, and cancer. These data may necessitate reevaluation of certain published data on patient-derived MPs and contribute to correct the clinical laboratory assessment of the presence and biologic functions of MPs in health and disease.

Artificial Alterations of Fluidity of Pea Thylakoid Membranes and Its Effect on Energy Distribution between Both Photosystems

1997 ◽  
Vol 52 (7-8) ◽  
pp. 475-480 ◽  
Keyword(s):  
Light Scattering ◽  
Energy Distribution ◽  
Benzyl Alcohol ◽  
Membrane Fluidity ◽  
Protein Complexes ◽  
Thylakoid Membranes ◽  
Scattering Intensity ◽  
Lower Extent ◽  
Light Scattering Intensity ◽  
Pigment Protein Complexes

Abstract Two different membrane perturbing agents -cholesterol and benzyl alcohol were applied to modify the fluidity of pea thylakoid membranes. Well pronounced decrease of membrane fluidity was observed upon increasing of cholesterol added. Rigification of thylakoid membranes was accompanied by reduction of cation-induced increase of light-scattering intensity and results in lower extent of increase of spillover upon cation induced stack-unstack transi­tion. Thylakoid membranes, treated with local anesthetic benzyl alcohol, showed an increase of membrane fluidity, but approximately the same behavior as untreated thylakoids in respect to the light scattering intensity dependence on cation concentration. Upon stack-unstack transition the observed changes of energy distribution for benzyl alcohol treated thylakoids are similar to those for controls. The data are discussed in terms of influence of membrane fluidity on lateral reorganization of pigment-protein complexes.

Electron Microscopy and image analysis of nucleo-protein complexes

1994 ◽  
Vol 52 ◽  
pp. 88-89
Author(s):  
E. H. Egelman ◽  
X. Yu
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Normal Cell ◽  
Genetic Recombination ◽  
Protein Complexes ◽  
Chromosomal Rearrangements ◽  
Reca Protein ◽  
E Coli ◽  
Helical Polymer ◽  
Specific Protease

The RecA protein of E. coli has been shown to mediate genetic recombination, regulate its own synthesis, control the expression of other genes, act as a specific protease, form a helical polymer and have an ATPase activity, among other observed properties. The unusual filament formed by the RecA protein on DNA has not previously been shown to exist outside of bacteria. Within this filament, the 36 Å pitch of B-form DNA is extended to about 95 Å, the pitch of the RecA helix. We have now establishedthat similar nucleo-protein complexes are formed by bacteriophage and yeast proteins, and availableevidence suggests that this structure is universal across all of biology, including humans. Thus, understanding the function of the RecA protein will reveal basic mechanisms, in existence inall organisms, that are at the foundation of general genetic recombination and repair.Recombination at this moment is assuming an importance far greater than just pure biology. The association between chromosomal rearrangements and neoplasms has become stronger and stronger, and these rearrangements are most likely products of the recombinatory apparatus of the normal cell. Further, damage to DNA appears to be a major cause of cancer.

Structure of contact sites between the outer and inner mitochondrial membranes investigated by HVEM tomography

1996 ◽  
Vol 54 ◽  
pp. 966-967
Author(s):  
C.A. Mannella ◽  
K.F. Buttle ◽  
K.A. O‘Farrell ◽  
A. Leith ◽  
M. Marko
Keyword(s):  
Liver Mitochondrion ◽  
Adenine Nucleotide ◽  
Protein Complexes ◽  
Mitochondrial Membranes ◽  
Electron Microscopic ◽  
Contact Sites ◽  
Transmission Electron ◽  
Precursor Proteins ◽  
Membrane Contacts ◽  
And Function

Early transmission electron microscopy of plastic-embedded, thin-sectioned mitochondria indicated that there are numerous junctions between the outer and inner membranes of this organelle. More recent studies have suggested that the mitochondrial membrane contacts may be the site of protein complexes engaged in specialized functions, e.g., import of mitochondrial precursor proteins, adenine nucleotide channeling, and even intermembrane signalling. It has been suggested that the intermembrane contacts may be sites of membrane fusion involving non-bilayer lipid domains in the two membranes. However, despite growing interest in the nature and function of intramitochondrial contact sites, little is known about their structure.We are using electron microscopic tomography with the Albany HVEM to determine the internal organization of mitochondria. We have reconstructed a 0.6-μm section through an isolated, plasticembedded rat-liver mitochondrion by combining 123 projections collected by tilting (+/- 70°) around two perpendicular tilt axes. The resulting 3-D image has confirmed the basic inner-membrane organization inferred from lower-resolution reconstructions obtained from single-axis tomography.

Reconstruction of Chitin-Protein Complexes Using Correlation Averaging Methods: Ovipositor of the Ichneumon Fly Megarhyssa

1980 ◽  
Vol 38 ◽  
pp. 38-39
Author(s):  
L. T. Germinario ◽  
J. Blackwell ◽  
J. Frank
Keyword(s):  
Protein Complexes ◽  
Hexagonal Lattice ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Insect Cuticle ◽  
High Dose ◽  
Wide Angle ◽  
X Ray ◽  
Averaging Methods ◽  
Digital Correlation

This report describes the use of digital correlation and averaging methods 1,2 for the reconstruction of high dose electron micrographs of the chitin-protein complex from Megarhyssa ovipositor. Electron microscopy of uranyl acetate stained insect cuticle has demonstrated a hexagonal array of unstained chitin monofibrils, 2.4−3.0 nm in diameter, in a stained protein matrix3,4. Optical diffraction Indicated a hexagonal lattice with a = 5.1-8.3 nm3 A particularly well ordered complex is found in the ovipositor of the ichneumon fly Megarhyssa: the small angle x-ray data gives a = 7.25 nm, and the wide angle pattern shows that the protein consists of subunits arranged in a 61 helix, with an axial repeat of 3.06 nm5.

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