M.F. Mallette

The isolation and some properties of the Forssman Hapten from sheep erythrocytes

Abstract Forssman hapten capable of precipitating specific antibody was isolated from stromata of erythrocytes of sheep. The product was found to be relatively pure. It melted with decomposition at 203–208 °, contained 2.92% nitrogen and less than 0.1% phosphorus, and possessed a molecular weight in the neighborhood of 1000. Galactose, chondrosamine, and lignoceric acid were tentatively identified in the acid hydrolyzate of the hapten. A basic component was not characterized.

The adaptive nature of the formation of lysine decarboxylase in Escherichia coli B

Abstract It has been conclusively established that the l -lysine decarboxylase of Escherichia coli B is formed adaptively in certain media containing l -lysine. Selection of a small fraction of the population during growth of a culture cannot be responsible for appearance of the enzyme. This conclusion is based on the appearance and disappearance of the enzyme in one and one and a half generations, respectively, and on decarboxylase formation in nonmultiplying cells. The latter observation depends upon a new approach, the use of sulfur mustard which blocks cell division but permits the formation of the adaptive enzyme. Treatment of cells with the ghosts of bacteriophage prevents adaptation to l -lysine. In the case of this enzyme, as has been reported for others, infection of the cells with bacteriophage also blocks the enzyme formation.

Purification and study of l-arginine decarboxylase from Escherichia coli B

Abstract The enzyme catalyzing the decarboxylation of l -arginine has been obtained from Escherichia coli and purified. The resulting fractions had high specific activities and were freed of lysine decarboxylase for the first time. Such samples contained an appreciable fraction of the enzyme as judged by sedimentation diagrams, but there was some material not sedimenting with the heavy component (active enzyme). A method is presented making it possible to correlate biological activity with a component located on a plate taken after partial sedimentation in a separation cell. Values of S 20 = 22 svedbergs and D 20 = 2.6 × 10 −7 sq. cm./sec. suggest a molecular weight of 780,000 for the enzyme. Some information on the effects of heat, acid, freezing and p -chloromercuribenzoate is presented.

A comparative study of the preparation and properties of ribonucleic acids of yeast

Abstract Highly purified preparations of ribonucleic acid have been obtained from bakers yeast employing newly modified methods of isolation. Solubility studies show that these materials are inhomogeneous, apparently containing a range of molecular structures of varying weight, and a dependence of solubility on molecular size is reported. It is suggested that homogeneous samples have never been obtained from cells. In addition, it is proposed tentatively that normal yeast cells possess a variety of ribonucleic acids and that known isolation methods modify the native structures thereby adding to the complexity of isolated preparations. The foregoing conclusion is supported by solubility studies designed to compare qualitatively the compositions of two different preparations of ribonucleic acid by examining an experimental mixture of these samples. The presence of common components in otherwise dissimilar and inhomogeneous preparations is suggested. Number-average molecular weights are reported for the various preprations with a value in one case of 66,000 after prolonged dialysis at 0 °C. This average size exceeds any recorded for preparations of the ribonucleic acid of yeast.

Activation of the Forssman hapten in the inhibition assay.

Abstract During isolation of the Forssman hapten from the stromata of sheep erythrocytes, activity measured by an inhibition assay disappeared and specific activity was reduced. This behavior was correlated with separation of the specific hapten and nonspecific activator. Purified hapten had a slight inhibitory action toward antibody but was extremely active in the presence of an inactive chromatographic fraction, an inactive extract of the stromata of beef erythrocytes, or phrenosine. Optimal activation was not reached in the present study.

A simple osmometer for the rapid determination of molecular weights

Abstract An easily constructed osmometer for the determination of molecular weights is described. The design is such that only 2–3 ml. of solution is required for a measurement. Osmotic equilibrium is rapidly reached, 3–8 hr. sufficing, depending upon the osmotic concentration, temperature, initial hydrostatic head, and membrane. Significant data may be obtained with pressures of 10 mm. or more of toluene. The method of preparation of the collodion membranes used is outlined. Molecular weights of 66,500 for bovine serum albumin and 36,000 for swine pepsin are reported.