Predicted charge of the complex of SLPI with various proteinases. Modelling of the SLPI molecule alone (A) and in complex with various proteinases (B-F): blue indicates positive charge, white is neutral and red indicates negative charge. All models are shown in the same orientation with views of opposite sides. The SLPI molecule was predominantly neutral with some positively-charged areas. Cathepsin G (D) formed the most positively-charged complex, followed by NE (C). Chymase (F) was strongly positively-charged on one surface only. Trypsin (B) had weak positive and negative charge on different surfaces, and tryptase (E) was strongly negatively-charged.