A Quantity Type Rotor for the Ultracentrifuge

Masket, A. V.

doi:10.1063/1.1769879

Cited by 11 publications

(5 citation statements)

References 7 publications

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“…However, small angles are not suitable for general clarification work with large non-diffusing particles, which will collect along the wall of the tube. Furthermore, special arrangements (11) to prevent overflow must be provided, or else space is wasted and tubes collapse easily; also the precision with which a boundary can be located is probably lower with small angles.…”

Section: Discussion Of Practical a Spects--from An Investigation Of mentioning

confidence: 99%

Sedimentation in the Angle Centrifuge

Pickels

1943

Journal of General Physiology

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1. Using hemocyanin from Limulus polyphemus as a test material, the process of sedimentation in the angle centrifuge, operating both in vacuum and in the open air, has been investigated. 2. Sedimentation in a given field of force was found less efficient when centrifugation was conducted in the open air, because of thermal convection. 3. Correlations have been made with results obtained in the analytical ultracentrifuge, and a theory of sedimentation in inclined tubes has been presented to explain the experimental results. 4. It has been shown that under proper conditions the angle centrifuge may be used for approximate determinations of particle size. 5. Recommendations, based mostly on experimental evidence, have been made for improving sedimentation and interpreting results. 6. To counteract convective disturbances of either thermal or inertial origin, a satisfactory method has been developed which consists of furnishing the fluid under study with a synthetic density gradient, formed with sucrose or some other non-sedimentable material.

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Section: Discussion Of Practical a Spects--from An Investigation Of mentioning

confidence: 99%

Sedimentation in the Angle Centrifuge

Pickels

1943

Journal of General Physiology

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“…The Beams type air-driven ultracentrifuge was used with a rotor holding 12 plastic tubes, each of one-half inch diameter and 8.2 ml. capacity, set at an angle of 100 from the axis of rotation (22,23). The centrifugation was performed at a speed of 800 revolutions per second, producing a mean centrifugal force of 130,000 G., for four hours, with about 23 minutes for acceleration and from 75 to 110 minutes for deceleration.…”

Section: Methodsmentioning

confidence: 99%

The Study of Serum Proteins and Lipids With the Aid of the Quantity Ultracentrifuge. I. Procedure and Principal Features of the Centrifugate of Untreated Normal Serum as Determined by Quantitative Analysis of Samples From Ten Levels 12

Turner¹,

Snavely²,

Goldwater³

et al. 1951

J. Clin. Invest.

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The studies described in this paper and some which follow have as an objective a better description of serum lipids. The present paper represents the first detailed report of work begun early in 1948, some features of which have been published in abstract (1)(2)(3)(4)(5). Initially our purpose was to extend the observations of Recant, Chargaff and Hanger (6) on the influence of serum proteins upon the cephalin-cholesterol flocculation and the thymol turbidity tests. We included quantitative analyses of the centrifugate for lipids as well as for proteins. It soon became apparent that we were using a procedure which was useful in the study of the structure and function of lipid complexes.As shown in the review by Edsall (7) there has long been evidence that a large proportion of the lipids of the serum occur not as small molecules, but as lipid aggregates, or lipoproteins, of varying complexity. The use of the ultracentrifuge, both quantitative and analytical, has a well established place in the study of serum lipids. Important contributions have been made by McFarlane (8,9), Pedersen (10, 11), the Harvard group (12) ment of rate of flotation when suspended in a standard medium, a technic which we have not used. Principal emphasis in published studies by other workers has been on centrifugation of treated serum. In the present paper we deal exclusively with centrifugation of untreated whole serum. At present it does not seem profitable to attempt a detailed comparison between the results obtained by our procedure on the one hand and those obtained by the system of analysis introduced by Cohn and his associates (21), and the results of the flotation procedures of others. When our studies of diseased states and normal individuals under dietary stress have been presented, such comparisons will be in order. Some of the similarities of our contributions to those of others will be mentioned below in the discussion.The perfect procedure for the study of serum proteins and lipids in the initial step would give complete separation of the different lipid and protein complexes, each entity in pure state with structure unchanged by the procedure effecting separation. We doubt if the procedure described in this communication separates any single lipid or protein complex in pure form; nevertheless, the concentration of complexes at certain levels in the centrifugate is of such a degree as to give new information concerning the structure of the complexes at that level and their concentration in the serum under study. The lipid distribution curves are reproducible within satisfactory limits with normal sera, and are significantly different in certain diseased states, especially in acute virus hepatitis, as we have already reported briefly (3) and will report later in detail. We believe our procedure has three main advantages: The manipulation of serum which effects redistribution of pro-1071 TURNER, SNAVELY, GOLDWATER, RANDOLPH, SPRAGUE, AND UNGLAUB teins and lipids is gentle and involves minimal risk of damage to complex molecul...

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“…The tubes are inclined at 10" to the axis of our centrifuge (Masket, 1941), so that sedimentation is across rather than down the tubes. Consequently, in one sense, a particle is sedimented when it has moved about 1 cm., but its final position depends on the readiness with which it slides down the wall of the tube.…”

Section: Ultracenh-ifugation Of Extractsmentioning

confidence: 99%

Observations on the Anomalous Proteins Occurring in Extracts from Plants Infected with Strains of Tobacco Mosaic Virus

Bawden

Pirie

1956

Journal of General Microbiology

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SUMMARY: When extracts from plants infected with various strains of tobacco mosaic virus were ultracentrifuged, the non-infective supernatant fluids still contained 0.5-5 yo of the protein serologically related to the viruses. The small, mostly spherical, particles aggregated to form short rods as the antigen was progressively purified by precipitation with acid or salts. It formed long rods when heated in pH 5-5 buffer or when incubated with trypsin. *4s the particles increased in length, their serological behaviour in precipitation tests changed from ' somatic' to 'flagellar' type.Purified preparations of the unsedimented antigen from plants infected with either of two virus strains contained 0.1-0.2~0 phosphorus, seemingly in the form of a ribose nucleic acid. No evidence was obtained that the preparations were mixtures containing some particles with the 0-5 yo phosphorus characteristic of infective virus and some particles of protein free from nucleic acid.One virus strain produced a higher ratio than the others of unsedimented to sedirnented antigen. The amount of unsedimented antigen was correlated with the total content of anomalous protein when the protein was increasing rapidly, but later it fluctuated unpredictably. No conditions were found that consistently favoured its accumulation, but when plants systemically infected with the type strain were kept a t 36", the total amount of antigen decreased, while the amount unsedimented sometimes increased.The proportion of the total antigen now obtained as poorly infective nucleoprotein is much less than 10 years ago, when a third of it sedimented in the ultracentrifuge but failed to compact into a pellet. Now the uncompacted sediment, with all the host plants and virus strains used, contains only a trivial part of the total antigen.The virus released into sap when leaves are minced is, weight for weight, more infective than the virus that remains in the leaf residues until it is released by fine grinding.The early work on the anomalous protein contained in virus-infected plants was done primarily to identify material that could be related to the viruses themselves, and its main aim was to make preparations with the maximum infectivity and the minimum of different components. Little attention was given to non-infective material, and the emphasis laid on the homogeneity of purified preparations served only to strengthen the general assumption that viruses multiply by the replication of an infecting particle to give a result that is uniform except for occasional variants regarded as equivalent to mutations. When we (Bawden & Pirie, 1945a, b ) found that plants infected with the Rothamsted tobacco necrosis virus or with tobacco mosaic virus (TMV) contained more than one type of anomalous protein, we questioned the validity of this assumption, and have since argued (Bawden & Pirie, 1950a, b, 1952, 1953 that infection is more usefully regarded as a change in the protein metabolism

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A Quantity Type Rotor for the Ultracentrifuge

Cited by 11 publications

References 7 publications

Sedimentation in the Angle Centrifuge

Sedimentation in the Angle Centrifuge

The Study of Serum Proteins and Lipids With the Aid of the Quantity Ultracentrifuge. I. Procedure and Principal Features of the Centrifugate of Untreated Normal Serum as Determined by Quantitative Analysis of Samples From Ten Levels 12

Observations on the Anomalous Proteins Occurring in Extracts from Plants Infected with Strains of Tobacco Mosaic Virus

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