Abstract
The present work is a continuation of the studies which have been carried out in this laboratory on the combination of proteins, amino acids, and allied compounds with the inorganic elements. 1 , 2 , 3 This work has now been extended to include the manganous compounds.
The method employed consists in adding the substances to be tested to a solution of manganous chloride. The solution is adjusted to pH 9.25 by means of a borate buffer. The aqueous solution is shaken for 20 minutes with a solution of isonitrosoacetophenone dissolved in chloroform. The color of the chloroform solution is compared in a colorimeter with a chloroform solution obtained in a similar manner except that the test substance is omitted. If the substance tested forms a compound with manganese (e. g., complex ions) such as to decrease the activity of the manganous ions in the aqueous phase, the color of the resulting chloroform solution will be less intense than the standard when both are shaken for a period of 20 minutes. If the manganous compound is dissociated to a greater extent no effect on the color will be observed.
The results show that oxalic, malonic, succinic, and glutaric acids have a decided influence in decreasing the color. The quantitative effect is greatest in the case of oxalic acid and least in the case of glutaric acid. The effect of the addition of aspartic or of glutamic acid is approximately the same as that of the corresponding nitrogen-free acids. The addition of alanine or of sodium chloride was without effect on the color. The effect of glycine was slight and that of glycylglycine slightly more, but not so great as that of the dicarboxylic acids.
The present work is being continued.
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