INTRODUCTIONAs a nonpolar amino acid, Valine (Val) is one of the most hydrophobic amino acids (Brosnan and Brosnan, 2006). Val, leucine, and isoleucine are called branched chain amino acids due to the branched chain structures of their R groups. In animals, Val serves as a precursor for the synthesis of protein and other amino acids (Ferrando et al., 1995). As a glucogenic amino acid, Val is a sub ...