Barrette-Ng IH, Ng KK-, Cherney MM, Pearce G, Ryan CA, James MNG. Structural Basis of Inhibition Revealed by a 1:2 Complex of the Two-headed Tomato Inhibitor-II and Subtilisin Carlsberg. Journal of Biological Chemistry. 2003 Jun;278(26):24062–71. doi: 10.1074/jbc.m302020200.