Article Information
PubMed
Related Articles
- Calcium-Induced Alterations in Mitochondrial Morphology Quan...Calcium-Induced Alterations in Mitochondrial Morphology Quantified in Situ with Optical Scatter Imaging
Biophysical Journal, Volume 83, Issue 3, 1 September 2002, Pages 1691-1700
Nada N. Boustany, Rebekah Drezek and Nitish V. Thakor
AbstractOptical scatter imaging (OSI), a technique we developed recently, was used to measure the ratio of wide-to-narrow angle scatter (OSIR) within endothelial cells subjected to calcium overload (1.6mM) after permeabilization by ionomycin. Within a few minutes of calcium overload, the mitochondria, which started as elongated organelles, rounded up into spherically shaped particles. This change in morphology was accompanied by a statistically significant 14% increase in OSIR in the cells’ cytoplasm. Mitochondrial rounding and OSIR increase were suppressed by cyclosporin A (25M), implying that the observed geometrical and scattering changes were directly attributable to the mitochondrial permeability transition. The angular scattering properties of a long mitochondrion rounding up were approximated by numerical simulations of light scatter from an ellipsoid rounding up into a sphere. The simulations predicted a relative increase in OSIR comparable to that measured experimentally for the case where the shape transition takes place with little or no volume increase. The simulations also suggested that mitochondrial refractive index changes could not account for the OSIR changes observed. Our data show that changes in OSIR correlate with mitochondrial morphology change in situ. OSI provides a new tool for subcellular imaging and complements other microscopy methods, such as fluorescence.
Abstract | Full Text | PDF (521 kb) - Effect of Glycerol on the Interactions and Solubility of Bov...Effect of Glycerol on the Interactions and Solubility of Bovine Pancreatic Trypsin Inhibitor
Biophysical Journal, Volume 76, Issue 5, 1 May 1999, Pages 2716-2726
Michael Farnum and Charles Zukoski
AbstractThe effects of additives used to stabilize protein structure during crystallization on protein solution phase behavior are poorly understood. Here we investigate the effect of glycerol and ionic strength on the solubility and strength of interactions of the bovine pancreatic trypsin inhibitor. These two variables are found to have opposite effects on the intermolecular forces; attractions increase with [NaCl], whereas repulsions increase with glycerol concentration. These changes are mirrored in bovine pancreatic trypsin inhibitor solubility where the typical salting out behavior for NaCl is observed with higher solubility found in buffers containing glycerol. The increased repulsions induced by glycerol can be explained by a number of possible mechanisms, all of which require small changes in the protein or the solvent in its immediate vicinity. Bovine pancreatic trypsin inhibitor follows the same general phase behavior as other globular macromolecules where a robust correlation between protein solution second virial coefficient and solubility has been developed. This study extends previous reports of this correlation to solution conditions involving nonelectrolyte additives.
Abstract | Full Text | PDF (145 kb) - Investigation on the Mechanism of Crystallization of Soluble...Investigation on the Mechanism of Crystallization of Soluble Protein in the Presence of Nonionic Surfactant
Biophysical Journal, Volume 89, Issue 6, 1 December 2005, Pages 4245-4251
Yanwei Jia, Janaky Narayanan, Xiang-Yang Liu and Yu Liu
AbstractThe mechanism of crystallization of soluble, globular protein (lysozyme) in the presence of nonionic surfactant CE (tetraoxyethylene glycol monooctyl ether) was examined using both static and dynamic light scattering. The interprotein interaction was found to be attractive in solution conditions that yielded crystals and repulsive in the noncrystallizing solution conditions. The validity of the second virial coefficient as a criterion for predicting protein crystallization could be established even in the presence of nonionic surfactants. Our experiments indicate that the origin of the change in interactions can be attributed to the adsorption of nonionic surfactant monomers on soluble proteins, which is generally assumed to be the case with only membrane proteins. This adsorption screens the hydrophobic attractive force and enhances the hydration and electrostatic repulsive forces between protein molecules. Thus at low surfactant concentration, the effective protein-protein interaction remains repulsive. Large surfactant concentrations promote protein crystallization, possibly due to the attractive depletion force caused by the intervening free surfactant micelles.
Abstract | Full Text | PDF (162 kb) - …more
Copyright © 1974 The Biophysical Society. All rights reserved.
Biophysical Journal, Volume 14, Issue 6, 439-453, 1 June 1974
doi:10.1016/S0006-3495(74)85925-4
Articles
Differential Light Scattering from Spherical Mammalian Cells
Albert Brunsting and Paul F. Mullaney
Abstract
The differential scattered light intensity patterns of spherical mammalian cells were measured with a new photometer which uses high-speed film as the light detector. The scattering objects, interphase and mitotic Chinese hamster ovary cells and HeLa cells, were modeled as (a) a coated sphere, accounting for nucleus and cytoplasm, and (b) a homogeneous sphere when no cellular nucleus was present. The refractive indices and size distribution of the cells were measured for an accurate comparison of the theoretical model with the light-scattering measurements. The light scattered beyond the forward direction is found to contain information about internal cellular morphology, provided the size distribution of the cells is not too broad.
