ABSTRACT
A thiamin-binding protein was isolated from wheat germ (Triticum aestivum). Its molecular mass was estimated as 120,000 Da consisting of two 56,000-subunits. The protein contained a large amount of glutamine or glutamic acid (15.4 mol%), arginine (12.5 mol%), and glycine (12.0 mol%). The levels of tyrosine, methionine, tryptophan, and cysteine in the protein were low. Optimum pH for its thiamin-binding activity was pH 8.0. It bound free thiamin specifically, not thiamin phosphates. The apparent dissociation and maximum bound values for the thiamin-binding were 2.52 μM and 9.34 nmol/mg of protein, respectively. Properties of the thiamin-binding protein from wheat germ were similar to those of the thiamin-binding protein from rice seeds, but not from buckwheat, sesame, or sunflower seeds.
