Separation of basolateral plasma membranes from smooth endoplasmic reticulum of the rat enterocyte by zonal electrophoresis on density gradients

Basolateral plasma membranes of rat small intestinal epithelium were purified by density gradient centrifugation followed by zonal electrophoresis on density gradients. Crude basolateral membranes were obtained by centrifugation in which the marker enzyme, (Na+ + K+)-ATPase, was enriched 10-fold with respect to the initial homogenate. The major contaminant was a membrane fraction derived from smooth endoplasmic reticulum, rich in NADPH-cytochrome c reductase activity. The crude basolateral membrane preparation could be resolved into the two major components by subjecting it to zonal electrophoresis on density gradients. The result was that (Na+ + K+)-ATPase was purified 22-fold with respect to the initial homogenate. Purification with respect to mitochondria and brush border membranes was 35- and 42-fold, respectively. Resolution of (Na+ + K+)-ATPase from NADPH-cytochrome c reductase by electrophoresis was best with membrane material from adult rats between 180 and 250 g. No resolution between the two marker enzymes occurred with material from young rats of 125 to 140 g. These results demonstrate that zonal electrophoresis on density gradients, a simple and inexpensive technique, has a similar potential to free-flow electrophoresis.

Zonal rotor ultracentrifugation: a proposal for improving the effectiveness of the procedure

A methodological variant of the zonal ultracentrifugation technique for the separation of plasma lipoproteins is described. The modification consists of (1) preloading the rotor with water and (2) using a different gradient former, and altering the gradient profile during the second step. This variant permits the detection of an intermediate lipoprotein even in healthy individuals and in cord blood.

The fractionation of suspensions of isolated hepatocytes by rate zonal centrifugation

Parenchymal cells, isolated from rat liver by a simple non-enzymic technique, were fractioned according to ploidy class by rate zonal centrifugation on sucrose density gradients. This method of fractionation applied to liver cells prelabelled in vivo with tritiated thymidine separated different size classes of cells synthesising DNA.

[Preparative isolation of polyribosomes from E. coli, and examination of their properties]

The paper describes a preparative method to produce polyribosomes from E. coli via their precipitation in a step-by-step sucrose gradient in the Ti-15 zonal rotor. Polyribosomes had the ability to translate mRNA in vitro. Polyribosomal proteins were isolated by the method of two-dimensional electrophoresis. The elongation factor EF-G was shown to occur in the polyribosomes.

Subcellular fractionation of human intestinal mucosa by large-scale zonal centrifugation. I. Characterization of subcellular organelles in the distal part of the ileum

The subcellular organelles in human ileal mucosa have been characterized by large-scale rate zonal and isopycnic density-gradient centrifugation. Mucosal scrapings were obtained from surgical specimens and the cells disrupted by extrusion under controlled pressure. The homogenized cells were then centrifuged to prepare a cell extract and the extract fractionated in a single-step procedure by zonal centrifugation on a continuous sucrose gradient. The subcellular organelles (brush borders, basal-lateral membranes, lysosomes, mitochondria, and endoplasmic reticulum) were located in the density gradient by assay of marker enzymes. Since a large number of analyses can be done on each fraction of interest, this fractionation technique may be used to study a variety of compounds and concepts involved in the subcellular physiology and pathology of human ileal mucosa.

Isolation and characterization of fourteen ribosomal proteins from small subunits of yeast

A method for preparation of a large amount of ribosomal subunits from Saccharomyces cerevisiae by a Ti-15 zonal rotor is described. The proteins of the small subunits (ca. 50 000 A260 units) were separated into 22 fractions by chromatography on carboxymethylcellulose columns. Fourteen proteins were then purified from the ten chromatographic fractions by filtration through Sephadex G-100 or Sephacryl S--200. The isolated proteins are YP 6, YP 7, YP 9, YP 12, YP 14', YP 14'', YP 28, YP 38, YP 45, YP 50, YP 52, YP 58, YP 63, and YP 70. The molecular weight and amino acid compositions of these proteins are presented.

A new gradient former and a simplified procedure for zonal centrifugation of immune complexes

A new gradient former for production of optimized sucrose gradients for B-XIV zonal rotors is described. Optimized gradients are gradients with an initial shelf to provide capacity and a shape that ensures isokinetic sedimentation conditions. By exhaustive computer calculations it has been found that optimized gradients can be produced by a very simple two-compartment gradient former. The design is given. Moreover, graphs for choice of gradient strength and run duration for preparative and analytical runs of samples containing soluble immune complexes are calculated. The new gradient former allows the use of a very simple procedure for zonal centrifugation.

High-resolution flow-zonal centrifuge system

A modified CF-32 Beckman flow centrifuge rotor has been developed that provides a long sedimentation path length with high gravitational force at the gradient sample interface. The modified rotor exhibits excellent separative capability and extraction efficiency when applied to purification of human influenza B and herpes simplex viruses.

Purification of the protein crystal from Bacillus thuringiensis by zonal gradient centrifugation

A method is described for the large-scale purification of the Bacillus thuringiensis protein crystal by zonal gradient centrifugation. NaBr gradients are employed in a Beckman J21-B centrifuge equipped with a JCF-Z rotor.

Isolation of subfractions of human very low density lipoproteins by zonal ultracentrifugation

Very low density lipoproteins (VLDL) have been isolated and subfractionated on the basis of their differing flotation rates. The procedure consists of a single 45-min zonal ultracentrifugation step using a linear density gradient of d = 1.00 to 1.15 g/ml. Appropriate fractions of the zonal rotor effluent containing the entire VLDL spectrum were characterized by analytical ultracentrifugation, gel filtration chromatography, and complete chemical analysis. Flotation rates of VLDL subspecies from hypertriglyceridemic and normolipemic plasmas correlated directly with their Stokes radii and triglyceride content and inversely with their proportion of cholesterol, cholesteryl esters, phospholipids, and total protein. There was also an inverse correlation of flotation rate with the fraction of tetramethylurea-insoluble protein. This procedure provides a reliable methodology for a rapid isolation of VLDL subfractions and the accurate determination of their flotation rates.

[Use of a zonal rotor for demonstrating that human myelin is formed by a continuum of particles of different densities]

Human myelin isolated from frozen brain consists of a continuum of particles as shown by sucrose continuous gradient (between 0,4 and 0,85 M) on zonal rotor. This was determined by measuring the O. D. at 260 and 280 millimicron, the protein concentration by Lowry method and sucrose concentration by polarimetry in 60 fractions. Most of the material is concentrated between 20-23% sucrose, the maximum being found at 21.5% (0.63 M). The fractions are dialyzed for 62 hrs. to remove the sucrose and the pellet obtained after centrifugation shows that the protein concentration increases from the ligher fraction to the heavier.

Synchronization of Escherichia coli by zonal centrifugation

A zonal centrifugation technique that can select the smallest newborn cells in an exponentially growing culture of Escherichia coli B/r is described.

Separation of subclasses of human serum high density lipoproteins by zonal ultracentrifugation

An improved one-step method for the preparative separation of three subfractions of high-density lipoproteins from normal human serum has been developed. It employs the method of rate zonal ultracentrifugation in a z-60 rotor using a discontinuous NaBr gradient in the density range of 1.0-1.4. The density gradients were monitored directly by a flow-through density meter allowing the direct read-out of the actual densities in the process of filling and emptying the rotor. The separation of the three density fractions from 5 to 15 ml serum was achieved during a single 12 hours run at 59.000 rpm. The three fractions showed characteristically different patterns on polyacrylamide gel electrophoresis and differences in their lipid and protein composition.

The construction and analysis of sucrose gradients for use with zonal rotors

The rate of sedimentation of a particle in a sucrose solution depends on the viscosity and density of the medium. These two variables are related to the sucrose concentration and the temperature of the medium by new simple equations. These equations were used in a rapid iterative procedure that relates the distance moved by a zone in a continuous sucrose gradient to its sedimentation coefficient. It is shown by comparison with experiment that this iterative method allows the distance moved by a zone to be calculated rapidly. The method may therefore be used to optimize the separation of particles in a sucrose-gradient-centrifugation experiment. The method also allows the unknown sedimentation coefficients of several zones to be measured from a single sucrose-gradient-centrifugation experiment.

Quantitation of the rate-zonal sedimentation spectrum

Rate-zonal sedimentation of cells from the female genital tract has been employed as a means of separating many of the different cellular components from each other. Ultra-slow streak photography of forward scattered light from the sedimentation spectrum has been used as a monitor of the success of the individual sedimentation maneuver. The presence of convention currents vitiates the separation potential of the technique, and this is readily detected by the photographic monitor. In addition, these photographs clearly indicate the positions of bands of cellular entities of different sedimentation velocities. Further study of the quantitative aspects of the light scattered from each part of the spectrum reveals that it possesses a quantitative representation of the concentration of cells at each level of the spectrum. The photographs and densitometric scans support these expectations. To avoid the limitations of film as a data-logging medium and to obtain real-time system utilization, a direct photoelectric scanner has been assembled. Preliminary tests indicate ready feasibility.

Zonal ultracentrifugation of plasma lipoproteins from normal and cholestatic pigs

The plasma lipoproteins in normal and cholestatic pigs were isolated by zonal ultracentrifugation and studied with respect to apoprotein and lipid composition. In contrast with the distribution in human plasma, only one HDL-population but two LDL-populations were demonstrated. No cholestatic lipoprotein similar to the human lipoprotein X was observed. HDL and the lighter LDL component were largely unchanged in cholestasis. The immunochemical properties were changed to some extent. Thus HDL-reacting material was found in the heavier LDL-component and VLDL after cholestasis but not before.

The effects of overloading in density-gradient centrifugation

The effects of overloading of the sample zone in density gradient centrifugation have been studied by use of a three-component shelf-lavered sample in which the total protein concentration was increased by addition of different amounts of albumin. It is found that overloading of the gradient gives rise to particle movements which are not predictable from the Svedberg equation. The two typical effects of overloading are dislocation of the zone mass centres and changes in the zone shapes. It is found that the magnitude of the calculated sedimentation coefficients increases nearly linearly with increasing sample load. The changes in zone shapes are found to depend on the specific load and two different patterns may be distinguished. The zone of the sample component which causes the overloading is defined as primarily overloaded and the others as secondarily overloaded. In primarily overloaded zones the original Gaussian shape is lost, while in secondarily overloaded zones the Gaussian zone shape is maintained, although a zone broadening is seen. Extreme high loads are found to be able to divide single zones. As a whole these experiments show that evidence for a non-overloaded set of experimental conditions must be provided, when density gradient centrifugation is used for determination of sedimentation coefficients. For preparative gradient centrifugations the power of resolution will decrease with increasing sample load. A simple method to detect overloading in density gradient centrifugations is described.

Age-related response to 1000 CCA unit zonally purified, inactivated influenza vaccines in volunteers in the U.S.A

Response to 1000 CCA unit Aichi/68 and Japan/57 influenza vaccines was studied in 687 volunteers from ages 6-101 in the summer of 1971. The vaccines, prepared by zonal ultracentrifugation, were well tolerated in all age-groups. Antibody responses were comparable with each vaccine and were strongly influenced by age of the volunteer. Persons born since 1940 (age 31 and under) had a much more impressive response as determined by both overall geometric mean titre rise and% with ≥ four-fold increase in titre than persons born before 1940. The most reasonable explanation for this phenomenon seems to be the greater prior exposure of the younger age-groups to the strains in the vaccines. It is concluded that more attention needs to be given in the future to assessing vaccine potency in the age-groups for which the maximum protection is desired, namely, the elderly.

Inactivated vaccines. 1. Volunteer studies with very high doses of influenza vaccine purified by zonal ultracentrifugation

In these studies very high doses (up to 4800 CCA units in adults) of formalin inactivated influenza vaccine purified by density gradient centrifugation were given safely to more than 5000 volunteers drawn from adolescent, middle aged and elderly populations. The relative paucity of reactions, compared with those groups receiving much lower doses of formalin-inactivated vaccine produced by Sharples centrifugation, suggests that reactions are due to non-viral substances rather than to toxic properties of the viruses, and that these substances are removable.

Homologous serum HI antibody responses increased with increasing vaccine dosage and there was no plateau effect at the higher dose level. In those groups studied, the appearance of neutralizing activity in post-vaccination nasal washings correlated closely with the higher vaccine doses and higher HI antibody titres.

The occurrence of the ‘Hong Kong flu’ epidemic in two of the groups, including over 3000 vaccine recipients, provided a unique opportunity to study the efficacy of the various vaccines used. Only those groups receiving high doses of a Hong Kong-like antigen (A2/Aichi/2/68) enjoyed significant reduction in illness (70%). Furthermore, there was a 90% reduction in the incidence of fever in that group.

These results indicate that very large doses of purified influenza vaccine can be given safely. Significant prevention and modification of disease caused by influenza via the vaccine approach is dependent on the administration of large doses of the appropriate antigen.