Conversion of Thiamine into Its Phosphoric Esters in Germinating Broad Beans.

Abstract

By the use of broad beans (seeds of Vicia faba L.), the distribution of thiamine and its phosphates in germs and seedlings was investigated at various growing stages. The results may be summarized as follows: Thiamine in dormant seeds is entirely in a free state, and concentrated mostly in germ axis (c.f., Table 1.). When germ axes, which are attached to or separated from the seeds, are soaked with water, free thiamine contained in them disappears and, in turn, thiamine phosphate comes into appearance, whereas this is not the case in soaked cotyledons lacking germ axes (Table 1 and 2). When isolated germ axis is soaked with water, the phosphate of thiamine that appears is not the diphosphate, but exclusively triphosphate alone (Table 3). Thiamine triphosphate can be detected in germ axis at a primary step of seed germination, while only the diphosphate at later stages (Table 4).
Consequently, it is surmised that thiamine triphosphate may act as a “sparkling substance” for the initiation of germinating process. In this connection, the recent finding described by T. Yusa^{2, 3)} is quite provocative, since the terminal phosphate group of thiamine triphosphate can be readily transferred to ADP resulting in the recovery of ATP.