Publication no. C-2000-0809-06R |  VIEW ARTICLE

Characterization of Thiamin-Binding Protein from Wheat Germ.

Takashi Adachi (1), Katsumi Watanabe (1), Toshio Mitsunaga (1,2). (1) Dept. of Food and Nutrition, Kinki University, Nara 631-8505 Japan. (2) Corresponding author. Phone: +81-742-43-1511. Fax: +81-742-43-2522. E-mail: <mitunaga@nara.kindai.ac.jp> Cereal Chem. 77(5):578-581. Accepted March 15, 2000. Copyright 2000 American Association of Cereal Chemists, Inc.

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.