title: The biological activity of alpha-1-antichymotrypsin: the change of chymotrypsin-inhibitory and immunoenhancing activities by heat treatment.
abstract: The relationship between chymotrypsin-inhibitory and immunoenhancing activity of alpha-1-antichymotrypsin was studied. alpha-1-Antichymotrypsin was treated at 50 degrees C, 55 degrees C or 60 degrees C for 15 min. It was found that antichymotryptic activity was reduced by half when alpha-1-antichymotrypsin was heated at 55 degrees C and was not detected at all when heating was carried out at 60 degrees C. alpha-1-Antichymotrypsin which was heated at 60 degrees C did not form a complex with chymotrypsin, but became a substrate for chymotrypsin. The effect of native and heated alpha-1-antichymotrypsin on antibody response was studied in mice. alpha-1-Antichymotrypsin increased the number of anti-sheep erythrocytes antibody producing cells even when it was heated at 60 degrees C. Circular dichroism and single radial immunodiffusion were used to detect conformational changes. Circular dichroism in the region of side chain absorption showed that the intensities of the spectra at 296, 284, and 265 nm decreased with a rise in temperature from 50 to 60 degrees C. In single radial immunodiffusion analysis, alpha-1-antichymotrypsin did not form a halo after being heated at 60 degrees C. In conclusion, when alpha-1-antichymotrypsin was heated at 60 degrees C, the immunoenhancing activity remained intact while the antichymotryptic activity was lost with the conformational change.
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D000917:Antibody Formation; D002918:Chymotrypsin / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D006358:Hot Temperature; D005779:Immunodiffusion; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011487:Protein Conformation; D000514:alpha 1-Antichymotrypsin
chemical_list: D000276:Adjuvants, Immunologic; D000514:alpha 1-Antichymotrypsin; D002918:Chymotrypsin