HIGHLY EFFECTIVE PROTEASE INHIBITORS FROM VARIANTS OF HUMAN PANCREATIC SECRETORY TRYPSIN-INHIBITOR (HPSTI) - AN ASSESSMENT OF 3-D STRUCTURE-BASED PROTEIN DESIGN

The results of a protein design project are used to compare different predictive strategies with respect to protein-protein interactions, We have been able to generate variants of human pancreatic secretory try psin inhibitor (hPSTI) optimized with respect to the affinity and spec ificity for human leukocyte elastase relative to trypsin and chymotryp sin, and in particular chymotrypsin, The extremely strong and specific human leukocyte elastase inhibitors were thus developed in three roun ds of mutagenesis and two rounds of 3-D modelling; only 24 variants in total were synthesized, although variations at seven different amino acid positions were involved (i.e. from 20(7) possible variants), An e xcellent elastase inhibitor could be designed with the minimum of two amino acid exchanges, The value of structural modelling and actual str ucture determination is discussed in the light of the experimental res ults of the designed protein variants and the results of tertiary stru cture determinations of the free variant and the inhibitor-protease co mplex. Particular reference is given to the strategy to be followed in protein design projects in general and to the development of protease inhibitors in particular.