STUDIES ON THE ANOMALOUS VISCOSITY AND FLOW-BIREFRINGENCE OF PROTEIN SOLUTIONS

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Abstract
An extensive investigation has been made of protein particle shape using the methods of flow-birefringence and anomalous viscosity measurement in the coaxial cell. The proteins may be divided into 4 groups. Group A consists of those which show flow-anomaly both in the bulk phase and in the surface film. These also show flow-birefringence in the bulk phase. Examples: tobacco mosaic disease virus nucleoprotein; myosin. Though corpuscular proteins, they have elongated particles before denaturation. Group B consists of those which show flow-anomaly only (in the first instance) in the surface film, and no flow-birefringence in the bulk phase. They are probably close to spherical in shape in soln., but form elongated particles as they denature in the surface films. After this process has been completed, they may show flow-anomaly also in the bulk phase. Some proteins show flow-anomaly in the surface film immediately as it forms, others only show it after a certain time has elapsed for the building up of the film. The former is designated as group B1 and the latter as group B2. To group B1 belong serum euglobulin and amphibian embryo euglobulin b. After the film of group B2 has once been fully formed and then dispersed by shaking, the soln. may have the properties of that of a protein in group B1; i.e., anomalous flow in the film may occur immediately on testing in the viscosimeter. To this group belong avian ovalbumin, and amphibian embryo pseudoglobulin. Group C consists of those proteins which show flow-anomaly neither in the bulk phase nor in the surface film; they are probably close to spherical in shape and include insulin, methaemo-globin, amphibian embryo euglobulin c, and mucoproteins. The theoretical significance of protein fibre molecules, whether native or formed by denaturation in the living cell, is discussed, especially in relation to exptl. morphology and cytology.