Olle Snellman

Biophysical and physiological investigations on cartilage and other mesenchymal tissues. II. The ultrastructure of bovine and human nuclei pulposi.

Electron microscopy of healthy nuclei pulposi indicates that the intercellular matrix should be regarded as a three-dimensional lattice gel system, containing a dense network of poorly differentiated collagenous fibrils and an amorphous interfibrillar substance. During aging, this system becomes subject to an irregular disappearance of the amorphous mucoid material, whereby the fibrils become partly unmasked. The mucoid interfibrillar material is probably responsible for the high water content and water-binding capacity.

Ultracentrifugal analysis of crystallised myosin

Our experiments show that crystallised myosin is accompanied by a rather small amount of impurities. Electron micrographs indicate that the myosin crystals are of anisotropic liquid nature. The myosin particles here appear to be aggregated to form long fibrils. An ultracentrifugal determination of the molecular weight gave a value of 1.5·106. The crystallised myosin is partly broken down into smaller fragments on treatment with urea for a length of time. On treating with urea for a short time the molecular weight is unaltered although other properties change; among others the myosin loses its power to form actomyosin.

Biophysical and physiological investigations on cartilage and other mesenchymal tissues. III. The diffusion rate of various substances in normal bovine Nucleus Pulposus.

Abstract By means of an interferometric method the diffusion rate of a number of salts and organic compounds has been determined in fresh sections of normal Nucleus pulposus from the intervertebral discs of young calves. Small and medium sized molecules diffuse only about half as rapidly in Nucleus pulposus as in water. Nucleus pulposus presents a gel structure with a variety of interfibrillar pores of different sizes. Available data indicate the average effective pore size to be about 15 A.

Electrophoretic investigations of crystallised myosin

Abstract The electrophoretic mobility of crystallised myosin in potassium chloride solutions shows no special characteristics compared with the conditions with other proteins. In solutions containing calcium or magnesium chloride the crystallised myosin migrates towards the negative electrode throughout the investigated pH range (pH 2–9). Whereas in KCl solutions an isoelectric point is found at pH 5.4 there is no indications of such a point for myosin dissolved in CaCl2. In salt mixtures, which so far are little studied, one can at one and the same pH (pH 7.4) obtain myosin which migrates towards either the negative or the positive electrode or which does not migrate at all, depending on the variation of the ratio K/Ca.

A contractile element containing tropomyosin (actotropomyosin)

Abstract The contractile element of the uterus body is shown to have composition other than that of the skeletal muscle. Only small amounts of myosin and actomyosin can be extracted. On short salt extraction, much tropomyosin appears in the solution and also free actin is found. On longer salt extraction, a complex called actotropomyosin can be obtained from the extract. The actotropomyosin reacts with ATP similarly to actomyosin. In its general behaviour it shows rough similarities with actomyosin but the differences between the two complexes are clear cut. On reprecipitation, the complex partly disintegrates and gradually loses its ability to react with ATP. Salting-out analyses of the complex show that it starts to precipitate at low salt concentrations but disintegrates. A part of it goes into solution and precipitates at higher ammonium sulphate concentrations. Salting-out curves of the material left in the solution after reprecipitation show that the supernatant contains a protein, which has been called the phosphate-absorbing protein, tropomyosins, and ribonucleic acid. The same result is obtained by an investigation of the material disintegrating from the ammonium sulphate and precipitating at higher salt concentrations. It is proposed that the actotropomyosin contains actin, the phosphate-absorbing protein and nucleic tropomyosin. The two latter components form a complex acting as myosin. The phosphate absorbing protein has enzymic properties when part of the complex. Some difference between the extractions from normal and gravid uterus are discussed.

Isolation and analysis of the large cytoplasmic granules of tissue mast cells

Abstract The large cytoplasmic granules of connective tissue mast cells have been isolated by a method of differential centrifugation. The chemical analysis of the selected washed granular fraction gave the following general composition (values in per cent): N 13.0, P 1.40, S. 0.39, proteins 72, lipids 23.9. Tests showed that anticoagulant properties were not present. Histamine was found to be connected with the granular fraction.

Ultracentrifugal studies of F-actomyosin

Abstract F-actomyosin has been investigated in the ultracentrifuge. It is a polydisperse substance. Two different main components are visible. One fraction has a very pronounced gel-like character and sediments very quickly. The other fraction shows a sedimentation picture characteristic of large long-chain molecules. Experiments carried out indicate that actomyosin is a stoichiometric compound of actin and myosin. The values obtained from ultracentrifuge and viscosity data indicate that actomyosin contains 1 part actin to 2.5–3 parts myosin.

An electron microscope study of myosin, actin, and acromyosin☆

Abstract In general the present work confirms the results of previous investigators. It shows further that the myosin molecules can form threads when high salt concentrations are not used. In other cases myosin will form a protein film. Only when enough acetone treatment has been used, is all the G-actin in globular form without the particles being clustered together. The fibrils of F-actin can build up very thin sheets when the polymerization occurs in the presence of a little MgCl2. Synthetic actomyosin consists of long threads thicker than threads of myosin or F-actin. They are often mingled together. If care is not taken to avoid contamination of too much myosin the latter will lay as a thin film over the actomyosin and make it not easily visible. Native actomyosin (B-myosin) investigated was always poorly visible on account of such a film. Actomyosin threads with ATP contract to jelly clusters in which it is not possible to see any structures. Actomyosin threads which do not contract have also been sees.

Ultracentrifugal studies of the myosin solutions of Greenstein and Edsall

Abstract An ultracentrifugal analysis of the myosin solution of Greenstein and Edsall shows that several components can appear. Some of these can possibly be attributed to actin, myosin and F-actomyosin. The nature of some components with intermediate sedimentation constants is not yet settled. Glycine buffers seem to alter the solutions in a definite manner so that several components appear. F-actomyosin was always deposited with a rather high sedimentation constant so it seems that native F-actomyosin must always be composed in a definite manner.

Salting-out curves of crystallized myosin

Abstract Salting-out measurement performed at 0° C on crystallized myosin show one main component precipitating between 37 adn 49% saturated ammonium sulphate. Another myosin component precipitating between 33–34% can be obtained by performing the measurements at higher temperature and also by some other means. A third component precipitating between 40–44% can also be obtained. This component contains more phosphorus and appears in the solution when sodium pyrophosphate has been added.