Comparison of the interactions of human α1-antichymotrypsin with human leukocyte cathepsin G and bovine chymotrypsin

The interactions of human α 1 -antichymotrypsin with human leukocyte cathepsin G and bovine chymotrypsin were investigated by means of circular dichroism spectroscopy and concurrent polyacrylamide gel electrophoresis. The mixtures were made in inhibitor excess at 0°C and studied at different times. Circular dichroism analyses indicated that within 10 min significant modifications had occurred in the aromatic environment of the components upon interaction. By SDS-polyacrylamide gel electrophoresis a complex having a M r near 80,000 was observed in both mixtures. By both methods it was demonstrated that these complexes were not stable.