**27. SBTX, a new toxic protein distinct from soyatoxin**

SBTX is a 44-kDa basic glycoprotein composed of a 27-kDa polypeptide chain and a 17 kDa polypeptide chain linked by a disulfide bond. The N-terminal sequences of the 44 and 27 kDa chains were identical. The secondary structure content was 35 % alpha-he‐ lix, 13% beta-strand and beta-sheet, 27 % beta-turn, 25 % unordered, and 1 % aromatic residues. SBTX lacked protease-inhibitory and hemagglutinating activities, but was im‐ munologically related to other toxic proteins, such as soyatoxin and canatoxin, and cross-reacted weekly with soybean trypsin inhibitor and agglutinin. It inhibited the growth of *Cercospora sojina*, a fungus causing frogeye leaf spot in soybeans at a concen‐ tration much lower than the lethal dose to mice. Thus it may be useful for the develop‐ ment of transgenic plants with augmented resistance to pathogens [30].
