scholarly journals Isolation, characterization and oxygen equilibrium of an extracellular haemoglobin from Eunice aphroditois (Pallas)

1976 ◽  
Vol 159 (1) ◽  
pp. 35-42 ◽  
Author(s):  
J V Bannister ◽  
W H Bannister ◽  
A Anastasi ◽  
E J Wood
Keyword(s):  
Minor Component ◽  
Sedimentation Equilibrium ◽  
Hill Coefficient ◽  
Electron Microscopic ◽  
Microscopic Appearance ◽  
Molecular Weights ◽  
Ph Values ◽  
Electron Microscopic Appearance ◽  
Ph Range ◽  
The Hill

The extracellular haemoglobin from the polychaeta,Eunice aphroditois, existed as a mixture of a heavy major component (so20, w = 56.96 +/- 0.125) and a light minor component (so20, w = 10.00 +/- 0.13S), the latter probably being a dissociation product of the former. The molecular weight of the purified heavier component, as detetermined by sedimentation equilibrium, was 3.44 X 10(6) +/- 0.04X10(6). The molecule had the electron-microscopic appearance typical of annelid haemoglobins, consisting of a stack of two hexagonal plates, with dimensions 26.32 +/- 0.27 nm across the flats of the hexagon, height of stack 17.86 +/- 0.34 nm. The sugar composition is reported, and the isoelectric point was approx. pH7.8. The haem content was 2.31 +/- 0.01%, corresponding to a minimal mol.wt. of 26700. Detergent/gel electrophoresis revealed the presence of at least four bands with molecular weights in the range 14600-31000. Five N-terminal amino acids were found. In addition to the 10S component, which co-existed with the 57S component at all pH values in the range 4.0-10.6, at low pH values (less than pH.5.0) A 16S and a 1.9 S component were found. The absorption and circular-dichroic spectra are reported, and the alpha-helical content, calculated from the ellipticity at 222 nm, was about 40%. The molecule bound O2 co-operatively with a maximum value of the Hill coefficient, h, of 3.9. Over the pH range 7.0-8.0 there was a positive Bohr effect.

Edward George Gray. 11 January 1924 – 14 August 1999

2002 ◽  
Vol 48 ◽  
pp. 151-165
Author(s):  
R.W. Guillery
Keyword(s):  
Nervous System ◽  
Three Dimensional ◽  
Electron Microscopic ◽  
Early Application ◽  
Microscopic Appearance ◽  
Wide Range ◽  
Neural Tissues ◽  
Synaptic Junctions ◽  
The Central Nervous System ◽  
Electron Microscopic Appearance

George Gray was an early contributor to our knowledge of the electron microscopic appearance of the central nervous system. He was skilful with the difficult techniques for preparing the tissues, worked rapidly, and was an astute observer. Sitting with him in the dark, staring at a dim image that George was moving rapidly as he searched for significant detail, could be an exciting experience. He had clear ideas about features that mattered and could quickly relate the two-dimensional electron microscopic images to the three-dimensional neural structures under investigation. He is best known for his detailed and perceptive description of synaptic junctions in the mammalian neocortex, and his name is still linked to two distinct junctional types (Gray's type 1 and Gray's type 2), now recognized as generally distinguishing excitatory from inhibitory junctions. He studied a wide range of neural tissues, played a significant role in the early isolation of ‘synaptosomes’, contributed greatly to the rapid advance of knowledge that accompanied the early application of the electron microscope to neural tissues, and influenced a great many later fine-structural studies of the nervous system.

scholarly journals Sedimentation-equilibrium studies on the heterogeneity of two β-lactamases

1970 ◽  
Vol 118 (3) ◽  
pp. 467-474 ◽  
Author(s):  
P. H. Lloyd ◽  
A. R. Peacocke
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficients ◽  
Minor Component ◽  
Theoretical Solution ◽  
Sedimentation Equilibrium ◽  
Equilibrium Studies ◽  
Molecular Weights ◽  
A Minor

Solutions of crystalline β-lactamase I and β-lactamase II, prepared by Kuwabara (1970), were examined in the ultracentrifuge and their sedimentation coefficients, diffusion coefficients, molecular weights and heterogeneity determined. Each sample was shown to consist of a major component comprising at least 97% of the material and a minor component of much higher molecular weight. The molecular weights of the major components were 27800 for β-lactamase I and 35600 for β-lactamase II. Emphasis is placed on a straightforward practical way of analysing the sedimentation-equilibrium results on mixtures of two macromolecular components rather than on a strict theoretical solution. Appendices describe the theory of systems at both chemical and sedimentation equilibrium and the procedure for calculating the combined distribution of two components.

Multivalent interaction between asialofetuin and plasma membrane preparations from the rat liver

1980 ◽  
Vol 58 (12) ◽  
pp. 1414-1420 ◽  
Author(s):  
Maria T. Debanne ◽  
Erwin Regoeczi ◽  
Mark W. C. Hatton
Keyword(s):  
Rat Liver ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
Theoretical Models ◽  
Underlying Mechanism ◽  
Marker Enzyme ◽  
Electron Microscopic ◽  
Microscopic Appearance ◽  
Wide Range ◽  
Electron Microscopic Appearance

Binding of bovine asialofetuin by rat liver plasma membranes was studied using different techniques for the separation of the free and bound forms of the glycoprotein and also different approaches to measure nonspecific binding. The membrane preparations had the electron microscopic appearance of a mixture of lamellae and vesicles and their lipid:protein ratios and marker enzyme profiles fell within the range of values available from the literature. The binding capacity was approximately 15 pmol of asialofetuin per milligram of membrane protein.Scatchard plots of the values obtained over a wide range of concentrations (4.8–12.6 μg asialofetuin per 30 μg membrane protein) after incubation at 22 °C showed pronounced non-linearity which, in combination with evaluations according to other theoretical models, was referable to heterogeneity of binding. In sharp contrast, after incubation at 4 °C the Scatchard plot was linear. This difference is interpreted as the expression of a functional, rather than a chemical, heterogeneity in asialofetuin binding. The underlying mechanism is thought to be competition of galactose groups for binding sites with the result that the number of bonds varies between the galactose groups of a bound asialofetuin molecule and the hepatic lectin, depending on the concentration of the glycoprotein in the incubation mixture.

scholarly journals REVERSIBLE AND IRREVERSIBLE CHANGES IN THE FINE STRUCTURE OF NERVOUS TISSUE DURING OXYGEN AND GLUCOSE DEPRIVATION

1965 ◽  
Vol 26 (3) ◽  
pp. 885-909 ◽  
Author(s):  
Henry deF. Webster ◽  
Adelbert Ames
Keyword(s):  
Synaptic Vesicles ◽  
Glucose Deprivation ◽  
Control Medium ◽  
Electron Microscopic ◽  
Microscopic Appearance ◽  
Oxygen And Glucose Deprivation ◽  
Golgi Membranes ◽  
Electrophysiological Measurements ◽  
Synaptic Changes ◽  
Electron Microscopic Appearance

Rabbit retinas were fixed for electron microscopy immediately after removing the eye and after incubations in a control medium and in three different deprivation media that were identical with the control except for the omission of glucose, oxygen, or both. A systematic comparison was made of the electron microscopic appearance of the different retinas with particular attention to four regions: rod inner segments, rod synapses, bipolar cell bodies, and ganglion cell myelinated axons. Retinas fixed after 1 hour of incubation in the control medium appeared virtually identical with those fixed immediately after ocular removal. Retinas deprived of oxygen and glucose for only 3 minutes showed generalized swelling of mitochondria and alterations in the structure of the synapses with loss of synaptic vesicles. Extending the combined deprivation caused further mitochondrial swelling and synaptic changes and also led to progressive swelling of the Golgi membranes and the granular endoplasmic reticulum. All these changes were almost completely reversible for up to 20 minutes but were irreversible by 30 minutes, at which time multiple discontinuities had appeared in cell and organelle membranes. Anoxia alone produced alterations similar to those found after somewhat shorter periods of the combined deprivation, whereas glucose withdrawal produced only minor changes. These electron microscopic results correlate quite well with previously reported electrophysiological measurements.

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