Abstract
1. The in vitro synthesis of aneurinpyrophosphate from added aneurin by the white and red cells of the blood of the rat and of man was studied. Though the synthesis is by no means negligible in human blood it is much higher in rat blood.
2. An average rat leukocyte contains
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about 160 times as much aneuripyrophosphate as an average rat erythrocyte. This ratio is increased to about 550 upon incubation of the blood with 1 mg aneurin per ml.
3. The synthesis in inhibited by oxalate, monoiodoacetate, fluoride and cyanide.
4. The synthesis by the red cells is preferentially inhibited by oxalate, the synthesis by the white cells by cyanide. This proves that the energy required for the synthesis of aneurinpyrophosphate from aneurin is mainly provided by glycolysis in the red cells and by respiration in the white cells.
5. Upon incubation of the blood with a small amount of aneurin a higher percentage is converted into aneurinpyrophosphate than with a large amount of aneurin. However, even from 0.1 gamma-aneurin added to 1 ml of blood only 26% is phosphorylated (from 1 mg added about 0.25% is phosphorylated).
6. During incubation of rat blood with aneurin at 39°C aneurin is not destroyed, nor are substances formed inhibiting aneurin pyrophosphate synthesis.
7. The synthesis of aneurinpyrophosphate by the erythrocytes depends upon the concentration of glucose present. It is decreased when the glucose concentration is below normal or extremely high.
8. The enzym system responsible for the synthesis of aneurinpyrophosphate from aneurin is badly damaged by incubating the blood at 39°C for some hours.
9. Attention is called to the fact that process producing energy are necessary for the conversion of a certain vitamin into its physiologically active form. As other vitamins form part of various enzymes connected with energy production insight into the interrelationship of various avitaminoses may be gained from investigations on the influence of the lack or one vitamin in the food on the conversion of another vitamin into its physiologically active form.
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