Single site proteolysis in silkworm antitrypsin causes structural changes in behavior against denaturing reagents.
Silkworm antitrypsin (sw-AT), which was thought to belong to serpin family, changed its behavior against denaturation after chymotryptic cleavage of a single peptide bond (Tyr-Val) two amino acids away from the reactive site for trypsin (Lys-Val). This chymotrypsin-modified sw-AT became resistant to denaturation by heat, sodium dodecyl sulfate, or guanidine hydrochloride, and this characteristic was evident in its circular dichroism spectrum. The modified sw-AT was also indigestible by S. aureus V8 protease. These facts should indicate a structural change from a stressed, unstable state to a stable one accompanying the cleavage of the single peptide bond in sw-AT. The stabilizing factor was in part attributed to the interaction of a COOH-terminal fragment (5 kDa) and an NH2-terminal one (36 kDa) in modified sw-AT.
Sasaki
T
T
Department of Food Science and Technology, School of Agriculture, Nagoya University, Japan.
Kohara
A
A
Shimidzu
T
T
Kobayashi
K
K
D000818:Animals; D012831:Bombyx; D002918:Chymotrypsin / Q000378:metabolism*; D002942:Circular Dichroism; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D006458:Hemolymph; D007700:Kinetics; D007814:Larva; D011487:Protein Conformation; D011489:Protein Denaturation; D012697:Serine Endopeptidases / Q000378:metabolism*; D000515:alpha 1-Antitrypsin / Q000378:metabolism*
D006146:Guanidines; D000515:alpha 1-Antitrypsin; D012697:Serine Endopeptidases; D002918:Chymotrypsin; C028344:glutamyl endopeptidase; D019791:Guanidine