On the synthesis of cocarboxylase

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Abstract
A method is described for the synthesis of cocarboxylase by the interaction of "bromo-aneurin" and silver pyrophosphate. Although no water was liberated during the reaction, the ratio of acid hydrolysable P:total P = l:4. This is interpreted as meaning that for each molecule of the primary pyrophosphoric ester (cocarboxylase) another molecule of the secondary symmetrical pyrophosphoric ester is formed. The same ratio of acid hydrolysable P: total P was found if the phosphorylation of aneurin was carried out by the method of Weijlard and Tauber, or by the interaction of "bromo-aneurin" and monosodium pyrophosphate. The separation of the primary and secondary pyrophosphoric esters was possible owing to the greater solubility of the phosphotungstate (or the reineckate) of the secondary ester in aq. acetone. A modified procedure of purification was described. The secondary pyrophosphoric ester was a very unstable and easily hydrolysable compound, since the substance isolated is aneurin monophosphate, as shown by titration. The catalytic activities of various samples of crystalline cocarboxylase prepared either by the new method or by the method of Weijlard and Tauber were identical, but were only 60% of the activity of natural cocarboxylase. Aneurin phosphates were precipitated in neutral soln. by the ions of several heavy metals. The reaction of aneurin and aneurin phosphates with nitrous acid was investigated. After 5 hr. about 80% of the theoretical amt. of N2 was evolved from aneurin, but much less from the phosphoric esters.

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