Expression and characterization of recombinant second domain variants of human mucus proteinase inhibitor (MPI).

The second, carboxyterminal domain of human mucus proteinase inhibitor (MPI) represents a strong antagonist of trypsin, chymotrypsin and leucocyte elastase. To modulate the inhibitory specificity and chemical stability of this domain, mutants have been prepared by site-directed mutagenesis of a cDNA fragment encoding for the carboxyterminal half of the inhibitor, followed by expression in E. coli. Inhibition assays with the purified recombinant domains revealed the possibility to create variants for potential pharmaceutical use.