THE DISTRIBUTION OF ACYLASES IN THE SEEDS OF HIGHER PLANTS

The presence of aminoacylase or aminoacylases in the seeds of a number of genera covering 25 families was demonstrated by employing the N-acetyl derivatives of 10 amino acids as substrate. Seeds selected from three families (Capparidaceae, Cruciferae, and Leguminosae) appeared to be the richest source of acylase. There was considerable difference in the amount of hydrolysis of the various N-acetyl amino acids. N-Acetyl-L-methionine was hydrolyzed by all the seed samples tested except one; three other N-acetylated amino acids (leucine, tyrosine, and alanine) were hydrolyzed to a lesser degree. N-Acetyl-L-proline was not attacked by any of the enzyme samples tested. The investigation demonstrated widespread distribution of the enzyme or enzymes responsible for the hydrolysis of the N-acetyl amino acids among plant seeds.

GLYCERIC ACID KINASE ISOLATED FROM A POLISH VARIETY OF RAPESEED (BRASSICA CAMPESTRIS L.)

Glyceric acid kinase from Polish variety rapeseed (Brassica campestris L.) was purified approximately 30-fold by ammonium sulphate fractionation and adsorption on alumina Cγ gel. The enzyme has a pH optimum at 7.9 and a pH stability range extending from 6.5 to 7.5. The maximum temperature for the reaction was 45 °C. The phosphorylation required ATP and a metal ion; Mg++ was slightly more effective than Mn++ and Co++, while Ni++ and Zn++ were ineffective. The Michaelis constants for the Mg–ATP complex and the substrate were 7.3 × 10−4 M and 1.6 × 10−3 M respectively. The reaction products, ADP and 3-phosphoglyceric acid, inhibited the phosphorylation. Sulphydryl reagents such as p-chloromercuribenzoate, o-iodosobenzoate, N-ethylmaleimide, and iodo-acetate completely inhibited the enzyme at low concentrations. 3-Phosphoglyceric acid was isolated and characterized from the enzyme reaction mixture.

Studies on the “Toxins” of Hemolytic Streptococci

For the test of the toxicity of anatoxin strongly Dick-positive reactors of younger ages or white pigs must be preferred, as they react only slightly, or do not react at all to nucleoproteins contained in the anatoxin. There is no practical method for the determination of the immunizing value of anatoxins. It must, therefore, be determined by the practical effect of preventive immunization. Concentration of anatoxin by means of two volumes of absolute alcohol in a normal salt solution containing 0.5 per cent phenol is the most convenient for the use of anatoxin, since this method not only eliminates formalin, but also diminishes substances other than toxin or toxoid which may be considered as a causal agent for the discomforts caused by the inoculation, and also since the dose of injection may be reduced to a great extent. The use of an anatoxin of moderate toxicity is more suitable, because the decrease in antigenicity follows more or less that in toxicity and the discomforts caused by inoculation of anatoxin may depend no less upon the protein substances contained in the anatoxin than upon the retained toxicity of the essential toxin itself. To reduce the toxicity to 1/1000th of its original toxicity, the action of 2 per cent formalin at 37°C. for thirty days, 1 per cent formalin at 45°C. for thirty days, or 2 per cent formalin at 45°C. for ten days are sufficient. The reduction of toxicity to 1/200 or 1/300th of its original toxicity could be brought out either by the action of 1 per cent formalin at 37°C. for thirty days, or 1 per cent formalin at 45°C. for ten days, or 0.5 per cent formalin at 45°C. for thirty days. The immunizing value of an anatoxin detoxified to 1/1000th of its original toxicity is only slight, whereas about 80 per cent of the children (five to thirteen years) had been successfully immunized by three injections (0.5, 1.0 and 1.5 cc.) of the anatoxins detoxified to 1/200th or 1/300th of their original toxicity. A 20-fold concentrated solution of an anatoxin prepared by dissolving precipitates caused by the addition of 2 volumes alcohol in normal saline solution containing 0.5 per cent phenol could be kept at least for three months without loss of its antigenic properties if kept in an ice box.

Studies on the “Toxins” of Hemolytic Streptococci

Skin reactions to the nucleoprotein of streptococcus seem to indicate a somewhat nonspecific allergic state of the individuals tested with this substance which seems to be common at least to various streptococci, and are not an indication of a specific relationship with certain streptococci. The fact that the allergy to the N.P. runs parallel to the immunity to the essential toxin is due to the structure of Streptococcus scarlatinae of which the N.P. and the essential toxin are the two components. But that both are not necessarily parallel to each other seems to depend upon the fact that nucloproteins are widely common to various sorts of streptococci while only a limited variety of streptococci can produce essential toxin and that the rapidity of development of immunity to the essential toxin and of allergy to the N.P. does not run parallel to each other. An explanation of many data reported by various authors on the Dick test contrary to the Dicks' theory may be found in the fact that the ordinary Dick toxin (culture filtrate) in addition to the essential toxin contains N.P. which is also capable of evoking allergic reactions on human skins. The culture filtrate which contains a considerable amount of N.P. seems to have given results inconsistent with the toxin-antitoxin theory. For the standardization of the Dick toxin for the Dick test it is not sufficient to determine its skin units, but the nucleoprotein content of it must be considered. In this respect, the Washington standard toxin was very satisfactory, but the use of the purified toxin free fron N.P. is most reasonable. In order to determine skin units of ordinary culture filtrate very young children with strongly positive reaction to the scarlatinal toxin are preferred, as they scarcely have a positive reaction to the nucleoproteins. If we utilize weak positive reactors and place the importance on the percentage of positive reactors, this will likely lead us into error, owing to the positive reactions to the N.P. The divergence of the results reported by many authors on the age distribution of positive reactors seems to depend upon the different content of nucleoproteins in the filtrate used.

On the Natural Immunity to Scarlet Fever of the Japanese and Chinese Residing in South Manchuria

Southern Manchuria, where the Chinese, as the native race and the Japanese, as immigrants, live under the same environment affords an appropriate field to study racial differences of natural immunity.

Experienced physicians here believe that the morbidity in scarlet fever of the Japanese is far greater than that of the Chinese. According to the investigation of antiscarlatinal committee of the Kwantung Government the morbidity of the Japanese residents is 3.06 per cent while that of the Chinese is only 0.12 per cent. These figures were obtained by dividing the number of scarlet fever cases occurring between 1921 and 1925 and treated by hospital and civil physicians attached to the S. M. R. Company by the number of the population living during the same period within the area under the jurisdiction of the Local Affairs Department of the S. M. R. Company. While these figures generally seem to be correct, the fact that there are some scarlet fever cases among the Chinese failing to make returns, should be taken into consideration.

Studies on the “Toxins” of Hemolytic Streptococci

Hemolytic streptococci isolated from pathologic foci, scarlatinal and non-scarlatinal, produce a toxic principle capable of evoking a cutaneous reaction in human subjects. Production of toxin varies considerably according to strains. Generally speaking, strains of hemolytic streptococci isolated from scarlet fever and erysipelas cases have been found to produce a toxic principle capable of evoking a marked cutaneous reaction in a larger proportion of human subjects tested than in the case of the toxins produced by suppurative streptococci. The toxins produced by various strains isolated from the same pathological conditions, e.g., scarlet fever, erysipelas or other suppurative lesions, may differ qualitatively when tested simultaneously on the same subject. If, therefore, only a small number of persons were tested simultaneously with two monovalent toxins of streptococcus hemolyticus from the same pathological conditions, the reactions to both toxins might be entirely similar or entirely dissimilar to each other. This dissimilarity may become more marked, if scarlatinal, erysipelas and suppurative toxins were compared in their monovalent form. But, in comparing the scarlatinal, erysipelas and suppurative toxins by skin reaction, we employed polyvalent toxin and demonstrated that the reactions to them were similar to the majority of cases tested. This similarity was marked in the greatest degree in the case of scarlatinal and erysipelas toxin, and marked in a lesser degree in the case of erysipelas and suppurative toxin, while it was not marked in the case of scarlatinal and suppurative toxin. The effectiveness of the toxin for both Dick test and preventive immunization depends largely on the selection of suitable strains. It seems to be reasonable to use polyvalent toxin by mixing toxins of several strains which are most potent in strength and inclusiveness.