BIOSYNTHESIS OF THIAMINE

I. BIOSYNTHESIS OF THIAMINE IN THE RADISH DURING GERMINATION OF ITS SEEDS

Abstract

1. 10^-7 M 2-methyl-4-amino-5-hydroxymethylpyrimidine (OMPm) or 2-methyl-4-amino-5-aminomethylpyrimidine (AMPm) together with 4-methyl-5-β-hydroxyethyl-thiazole (MHT) was added to the homogenates of sprouting peas, sprouting beans, clovers, potatoes, onions, scallions and germinating radishes, and the pH was adjusted to 5.0, followed by incubation for 3 hours at 37° and the thiamine production was determined.
In the germinating radishes 0.4-1.6mg thiamine per 10g samples was produced after addition of OMPm and MHT, corresponding to 26-77% increase of thiamine content.
2. Sand culture of germinating radishes after addition of OMPm, AMPm, 2-methyl-4-amino-5-formylpyrimidine (FP) or 2-methyl-4-amino-5-carboxylic acid-pyrimidine (CAP) to MHT showed that OMPm was most effective for producing thiamine, more than twice as much being produced as the controls, followed by FP and AMPm.
3. The same experiment using cysteine or methionine instead of MHT in the presence of OMPm resulted in less production of thiamine than that of MHT. MHT, therefore could not be replaced by cysteine or methionine.
4. Thiamine production in germinating radishes in sand culture was further compared in 4 groups, i.e., addition of OMPm alone, addition of both OMPm and MHT, addition of MHT alone, and without any addition. As for the weight, dry matter, length, and nitrogen content of the sprout, no marked difference was found among the 4 groups, but the amount of thiamine was about 3 times as great in the presence of OMPm and MHT, somewhat greater in the presence of OMPm, and about the same in the presence of MHT as the controls.