Changes In Total Protein Content Research Articles

Studies on Protein Metabolism in Higher Plants

Changes in ribulose diphosphate (RuDP) carboxylase activity and the content of fraction 1 protein, which had been elucidated to be identical with protein of RuDP carboxylase, in tobacco leaves were examined with age, comparing with change in total protein content. Fraction 1 protein was determined by an immunological precipitin method developed in this experiment. Fraction 1 protein decreased with age and the rate was similar or a little larger than those of total protein and total chlorophyll. The carboxylase activity decreased more rapidly than fraction 1 protein during the senescent process. In a plant, upper leaves showed higher values of the carboxylase activity and fraction 1 protein content than lower leaves. The specific activity, RuDP carboxylase activity per unit fraction 1 protein, in upper leaves was higher than that in lower leaves.

Studies on the mucoproteins of human parotid saliva

Two cationic mucoprotein fractions from parotid saliva were separated by paper electrophoresis and analysed for amino acids. The two fractions had a similar composition. The major amino acids were proline, glycine and glutamic acid in a molar ratio of about 3:2:2. The tyrosine content was very low. When the FolindashCiocalteu and the biuret reaction were compared for protein estimation of total parotid saliva and separated fractions the biuret values were usually about 1.4 times as high for the total saliva, 2 times as high for the mucoprotein fractions and about the same for the amylase fraction. Studies of the relation of the various nondialysable carbohydrate components of parotid saliva to total protein content and to rate of flow disclosed that: (a) there was a high correlation between changes in amounts of nondashdialysable carbohydrates and changes in total protein content and (b) there was a very low correlation between changes in amounts of carbohydrates and protein and changes in flow rate.

Reversion of L forms and spheroplasts of Proteus mirabilis.

Altenbern, Robert A. (U.S. Army Chemical Corps, Fort Detrick, Frederick, Md.). Reversion of L forms and spheroplasts of Proteus mirabilis. J. Bacteriol. 85:269-272. 1963.-Spheroplasts or 3-B type L forms of Proteus mirabilis formed by growth in the presence of penicillin are able to revert to the bacillary form, as judged by regain of resistance to osmotic shock. Reversion takes place in the absence of exogenous nutrients, although at a lesser rate than that observed in a nitrogen-rich medium. Either chloramphenicol or 6-azauracil can completely inhibit reversion of spheroplasts in a penicillin-free medium. By direct measurement, there was no detectable change in total protein content throughout the period of reversion of a spheroplast suspension. Assay for acid-insoluble diaminopimelic acid (DAP) revealed that a large part of the DAP of the cell wall of normal cells was lost when the cells were converted to spheroplasts by exposure to penicillin. Upon transfer to penicillin-free medium, there was a rapid increase in acid-insoluble DAP in the wall of the reverting spheroplast. When spheroplasts were transferred to penicillin-free medium containing chloramphenicol, the acid-insoluble DAP in the wall of the spheroplast continued to decrease. The significance of these results in regard to sites of activity of the antibiotics involved is discussed.