[Properties of thiamine-binding proteins isolated from rat brain, liver and kidneys].

The study of thiamine-binding proteins (ThBP) isolated from liver and kidneys of rats was held in order to find out the peculiarities and physiological role of the ThBP isolated earlier from the rat brain. It was demonstrated that ThBP from liver and kidneys of rats as well as ThBP from rat brain described earlier, were bifunctional: on an equal footing with ability to bind thiamine specifically, they show an ability to hydrolyse the phosphoric esters of thiamine selectively. The ThBP of these tissues (liver, kidneys and brain) didn't differ by the molecular weight, but differed by the enzymatic activities. The molecular weight of ThBP was estimated to be 100 kDa by gel-filtration; 63 kDa and 35 kDa by sodium dodecylsulfate gel electrophoresis. Specific thiamine-binding activity increases as follows: ThBP from rat brain < ThBP from rat liver < ThBP from rat kidneys.