The Optical Activity, Scattering, and Viscosity of Erythrocyte Membranes

1972 ◽  
Vol 50 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Jacob A. Verpoorte ◽  
Frances M. Smith
Keyword(s):  
Optical Activity ◽  
Membrane Structure ◽  
Salt Effect ◽  
Optical Rotation ◽  
Sodium Dodecyl ◽  
Erythrocyte Membranes ◽  
Lower Viscosity ◽  
Concentration Changes ◽  
Free Membrane ◽  
Electrostatic Repulsions

The optical properties of erythrocyte membranes prepared by osmotic hemolysis in the presence of EDTA (ethylenedinitrilotetraacetic acid) were studied and found to be dependent upon salt concentration. Changes in optical rotation and circular dichroism as a result of addition of NaCl were accompanied by an increase in turbidity and a decrease in pH and viscosity of the membrane suspensions. Solubilization of membranes by sodium dodecyl sulfate (SDS) resulted in a lower viscosity and loss in turbidity but had little effect on optical activity. n-Butanol-extracted soluble membrane proteins had optical activities similar to those of salt-free membrane suspensions. Addition of SDS to membranes or extraction with butanol completely eliminated the salt effect on the rotation and dichroism spectra. It is proposed that salt reduces electrostatic repulsions between phospholipid molecules favoring the formation of a more compact membrane structure with reduced hydration.

scholarly journals Hydrogen-ion titration studies on erythrocyte membranes

1976 ◽  
Vol 156 (1) ◽  
pp. 159-165 ◽  
Author(s):  
C Hallam ◽  
J M Wrigglesworth
Keyword(s):  
Membrane Structure ◽  
Plasma Membranes ◽  
Sodium Dodecyl ◽  
Spectrophotometric Assay ◽  
Hydrogen Ion ◽  
Erythrocyte Membranes ◽  
Chemical Treatments ◽  
Before And After ◽  
Selective Chemical ◽  
Ionizable Groups

1. H+ titration was used to detect the presence of ionizable groups on human erythrocyte plasma membranes. Between pH2.9 and 11.3, two significant peaks of H+ association/dissociation occur in the differential from of the titration curve, one at pH3. 1. And the other at pH10.3. 2. After disruption of membrane structure by exposure to high pH or by the addition of sodium dodecyl sulphate, maxima of H+ association/dissociation were seen at pH3.1,4.3,6.5,10.3 and 10.7. 3. Spectrophotometric assay and selective chemical treatments were used to identify several of the titratable residues. 4. The degree of eleectrostatic interaction between titratable charged groups was investigated by comparing the titration characteristics of the membranes before and after modification of membrane structure.

Transmembrane phospholipid distribution revealed by freeze-fracture replica labeling

1996 ◽  
Vol 109 (10) ◽  
pp. 2453-2460 ◽  
Author(s):  
K. Fujimoto ◽  
M. Umeda ◽  
T. Fujimoto
Keyword(s):  
Plasma Membranes ◽  
Membrane Lipids ◽  
Secretory Granules ◽  
General Scheme ◽  
Sodium Dodecyl ◽  
Freeze Fracture ◽  
Electron Microscopic Observation ◽  
Erythrocyte Membranes ◽  
Electron Microscopic ◽  
Intracellular Membranes

We propose the use of membrane splitting by freeze-fracture for differential phospholipid analysis of protoplasmic and exoplasmic membrane leaflets (halves). Unfixed cells or tissues are quick-frozen, freeze-fractured, and platinum-carbon (Pt/C) shadowed. The Pt/C replicas are then treated with 2.5% sodium dodecyl sulfate (SDS) to solubilize unfractured membranes and to release cytoplasm or contents. While the detergent dissolves unfractured membranes, it would not extract lipids from split membranes, as their apolar domains are stabilized by their Pt/C replicas. After washing, the Pt/C replicas, along with attached protoplasmic and exoplasmic membrane halves, are processed for immunocytochemical labeling of phospholipids with antibody, followed by electron microscopic observation. Here, we present the application of the SDS-digested freeze-fracture replica labeling (SDS-FRL) technique to the transmembrane distribution of a major membrane phospholipid, phosphatidylcholine (PC), in various cell and intracellular membranes. Immunogold labeling revealed that PC is exclusively localized on the exoplasmic membrane halves of the plasma membranes, and the intracellular membranes of various organelles, e.g. nuclei, mitochondria, endoplasmic reticulum, secretory granules, and disc membranes of photoreceptor cells. One exception to this general scheme was the plasma membrane forming the myelin sheath of neurons and the Ca(2+)-treated erythrocyte membranes. In these cell membranes, roughly equal amounts of immunogold particles for PC were seen on each outer and inner membrane half, implying a symmetrical transmembrane distribution of PC. Initial screening suggests that the SDS-FRL technique allows in situ analysis of the transmembrane distribution of membrane lipids, and at the same time opens up the possibility of labeling membranes such as intracellular membranes not normally accessible to cytochemical labels without the distortion potentially associated with membrane isolation procedures.

scholarly journals Optical rotatory power. I—A theoretical calculation for a molecule containing only isotropic refractive centres

1934 ◽  
Vol 144 (853) ◽  
pp. 655-675 ◽  
Keyword(s):  
Theoretical Calculation ◽  
Optical Activity ◽  
Chemical Structure ◽  
Central Atom ◽  
Optical Rotation ◽  
Rotatory Power ◽  
Theoretical Formula ◽  
Optical Rotatory ◽  
Present Communication ◽  
Optical Rotatory Power

Ever since the time of van’t Hoff and Le Bel the number investigations dependent on optical activity, or attempting to elucidate optical activity, has been very great, and it is remarkable that, even at the present time, there is no theoretical formula which gives the relation between the magnitude of the rotation and the chemical structure of the molecule concerned. The present communication supplies this want with regard to the molecule of the simplest asymmetric type: the molecule with four different groups attached to one central atom. Various special hypothese have been postulated to explain optical activity, but a few investigators have shown quite definitely that there is no necessity for any of these hypotheses. Born* and Oseen have shown independently that, if the molecule has a dissymmetric structure, the ordinary refractive properties of the atoms will account for an optical rotation. Gray* and de Mallemann have attempted calculations of formulæ for optical retatory power on this basis. However, it has not been possible to condense the numerous algebraic terms which occur in these calculaations into a compact form.

scholarly journals Enhanced gyrotropic birefringence and natural optical activity on electromagnon resonance in a helimagnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. Iguchi ◽  
R. Masuda ◽  
S. Seki ◽  
Y. Tokura ◽  
Y. Takahashi
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Optical Activity ◽  
Optical Rotation ◽  
Magnetoelectric Coupling ◽  
Optically Active ◽  
Crystalline Solid ◽  
Spin Order ◽  
Active Devices ◽  
Principal Axes

AbstractSpontaneous symmetry breaking in crystalline solid often produces exotic nonreciprocal phenomena. As one such example, the unconventional optical rotation with nonreciprocity, which is termed gyrotropic birefringence, is expected to emerge from the magnetoelectric coupling. However, the fundamental nature of gyrotropic birefringence remains to be examined. Here w`e demonstrate the gyrotropic birefringence enhanced by the dynamical magnetoelectric coupling on the electrically active magnon resonance, i.e. electromagnon, in a multiferroic helimagnet. The helical spin order having both polarity and chirality is found to cause the giant gyrotropic birefringence in addition to the conventional gyrotropy, i.e. natural optical activity. It is demonstrated that the optical rotation of gyrotropic birefringence can be viewed as the nonreciprocal rotation of the optical principal axes, while the crystallographic and magnetic anisotropies are intact. The independent control of the nonreciprocal linear (gyrotropic birefringence) and circular (natural optical activity) birefringence/dichroism paves a way for the optically active devices.

scholarly journals Twins in YAl3(BO3)4 and K2Al2B2O7 Crystals as Revealed by Changes in Optical Activity

Crystals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Johannes Buchen ◽  
Volker Wesemann ◽  
Steffen Dehmelt ◽  
Andreas Gross ◽  
Daniel Rytz
Keyword(s):  
Optical Properties ◽  
Optical Activity ◽  
Nonlinear Optical ◽  
Frequency Conversion ◽  
Optical Rotation ◽  
Visible Spectrum ◽  
Rotatory Power ◽  
Nonlinear Optical Properties ◽  
Crystal Quality ◽  
Optical Rotatory Dispersion

Many borate crystals feature nonlinear optical properties that allow for efficient frequency conversion of common lasers down into the ultraviolet spectrum. Twinning may degrade crystal quality and affect nonlinear optical properties, in particular if crystals are composed of twin domains with opposing polarities. Here, we use measurements of optical activity to demonstrate the existence of inversion twins within single crystals of YAl 3 (BO 3 ) 4 (YAB) and K 2 Al 2 B 2 O 7 (KABO). We determine the optical rotatory dispersion of YAB and KABO throughout the visible spectrum using a spectrophotometer with rotatable polarizers. Space-resolved measurements of the optical rotation can be related to the twin structure and give estimates on the extent of twinning. The reported dispersion relations for the rotatory power of YAB and KABO may be used to assess crystal quality and to select twin-free specimens.

scholarly journals OPTICAL ROTATION AND HELICAL POLYPEPTIDE CHAIN CONFIGURATION IN COLLAGEN AND GELATIN

1955 ◽  
Vol 1 (3) ◽  
pp. 203-214 ◽  
Author(s):  
Carolyn Cohen
Keyword(s):  
Optical Activity ◽  
Optical Rotation ◽  
Specific Rotation ◽  
X Ray Diffraction ◽  
Citrate Buffer ◽  
Gelatin Films ◽  
Dispersion Data ◽  
Single Term ◽  
Native Collagen ◽  
Helical Configuration

The optical rotation phenomena exhibited by a citrate-extracted fraction of ichthyocol (from carp swim bladder), as well as by the parent gelatin derived therefrom, have been studied. Dispersion data for all cases follow a single-term Drude equation, but the variations with state are adequately expressed by simple reference to changes in [α]D as follows:— 1. The native collagen fraction, dispersed in 0.15 M citrate buffer at pH 3.7 in the cold (11°C.), yields a high negative specific rotation, [α]D, near –350°. 2. During equilibration at 40°C., which causes conversion to a monodisperse parent gelatin, the rotation drops to about –110°. 3. Gelation at 2°C. results in a partial regain of rotation to around –290°. This mutarotation is reversible, depending on temperature. 4. In the range 0.02 to 0.28 per cent the native ichthyocol and the warm gelatin solutions show little concentration dependence, but with the cold gelatin solutions the specific rotation increases with concentration. Gelatin films formed by cold evaporation yield high specific rotation (ca. –620°), but those formed by hot evaporation retain low optical activity. 5. Since this same collagen-gelatin system has been investigated physicochemically, it is possible to relate molecular changes to the observed variations in optical rotation. Conclusions are similar to those of Robinson (1953), who studied other gelatins: high negative rotation is believed related to a native collagen polypeptide configuration, herein specified as helical (from x-ray diffraction considerations) and destroyed by heating. The possible roles of intermolecular interactions and of prevalent pyrrolidine constituents in influencing the helical configuration and optical activity are discussed.

scholarly journals Interference-contrast optical activity: a new technique for probing the chirality of anisotropic samples and more

2020 ◽  
Vol 7 (5) ◽  
pp. 192201 ◽  
Author(s):  
R. P. Cameron ◽  
U. Vogl ◽  
N. Trautmann
Keyword(s):  
Pharmaceutical Industry ◽  
Optical Activity ◽  
Optical Rotation ◽  
New Technique ◽  
Future Research ◽  
Linear Birefringence ◽  
New Class ◽  
Potential Applications ◽  
A New Technique ◽  
Chiral Crystals

We introduce interference-contrast optical activity (ICOA) as a new technique for probing the chirality of anisotropic samples and more. ICOA could underpin a new class of ‘chiral microscopes’, with potential applications spanning the range of chirality and beyond. Two possible versions of ICOA are described explicitly; one designed to probe the optical rotation of a transparent sample regardless of the sample’s linear birefringence (ICOA-OR) and another designed to probe gradients in the optical rotation of a transparent sample (ICOA-GOR). Simulated results for α -quartz lead us to suggest that ICOA-GOR might be applied to help monitor the growth of chiral crystals in the pharmaceutical industry. Possible directions for future research are highlighted.

Origin of the optical activity of silver thiogallate

2000 ◽  
Vol 33 (1) ◽  
pp. 126-129 ◽  
Author(s):  
J. Etxebarria ◽  
C. L. Folcia ◽  
J. Ortega
Keyword(s):  
Circular Dichroism ◽  
Optical Activity ◽  
Room Temperature ◽  
Optical Rotation ◽  
Linear Dichroism ◽  
Optical Data ◽  
Point Dipole ◽  
Reliable Measurement ◽  
Photoelastic Modulator ◽  
Circular Dichroïsm

Using a high-accuracy universal polarimeter, the birefringence and optical activity of AgGaS2have been determined between 300 and 500 K. The optical rotation has been found to be 94° mm−1at room temperature for a wavelength of 632.8 nm. This value is unexpectedly small if compared with values close to 1000° mm−1at 485 nm reported previously. The present optical data are well explained using a point-dipole model for the calculation of the refractive indices and optical activity. The main contributors to the optical rotation are the S atoms. However, these atoms are not at positions especially suitable to promote extremely large gyrations. Consequently, the size of the optical rotation reported before in the blue part of the spectrum is presumably due to the existence of a circular dichroism band close to that region. Using an optical system based on a photoelastic modulator, a strong linear dichroism peak has been measured in the range 450–500 nm. This fact has prevented reliable measurement of the circular dichroism.

Studies of the optically active compounds of Anacardiaceae exudates. II. The action of Alkali on the long-chain alicyclic Keto Alcohol of Tigaso Oil

1958 ◽  
Vol 11 (1) ◽  
pp. 64 ◽  
Author(s):  
LK Dalton ◽  
JA Lamberton
Keyword(s):  
Optical Activity ◽  
Active Compound ◽  
Optical Rotation ◽  
Large Change ◽  
Optically Active ◽  
Bicyclic Compound ◽  
Compound I ◽  
Alcoholic Alkali ◽  
Rapid Reaction ◽  
Long Chain

In cold alcoholic alkali the optically active compound I from Tigaso oil undergoes a rapid reaction which involves loss of its conjugated carbonyl system, and a large change, with inversion, of its optical rotation. The reaction is interpreted as a cyclization and the product is provisionally formulated as a bicyclononane derivative IIa. In hot alcoholic alkali, IIa is not the final product ; the bicyclic compound undergoes further reaction to give a mixture in which the unsaturated monocyclic triketone VII (R=C16H31) appears to predominate, but which probably consists of a mixture of VII and VIII (R=C16H31). These can be hydrogenated to a mixture of saturated monocyclic triketones VII and VIII (R =C16H33). The same hydrogenated triketones are obtained if IIa is first hydrogenated and then heated with alcoholic alkali. These triketones are optically active and by oxidation with hypobromite, or with permanganate and then hypobromite, yield bromoform and the chemically homogeneous tribasic acid IX, which still retains optical activity. The isolation of the saturated hydroxydiketone IIb in 4 per cent, yield from hydrogenated Tigaso oil suggests that 11% is present to that extent in the original oil.

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