Limited proteolysis of silkworm antitrypsin by several proteinases.
Silkworm antitrypsin (sw-AT) isolated from larval hemolymph was limitedly digested by Achromobacter lysylendopeptidase, alpha-chymotrypsin, subtilisin BPN', subtilisin Carlsberg, papain, or Pseudomonas elastase. Each proteinase could cleave specific site(s) around the reactive site identified for the reaction of sw-AT and bovine trypsin. Among these proteinases, only subtilisin BPN' was inhibited by sw-AT, although weakly. By the cleavable amino acid sequence in sw-AT, it was suggested that whether or not these proteinases were inhibited by sw-AT did not solely depend on their substrate specificities. The susceptibility to the attack of proteinase should indicate that this region is exposed on the molecular surface. The amino acid sequence in the COOH-terminal region slightly away from the reactive site in sw-AT had homology with that in the corresponding region of the serine proteinase inhibitor (serpin) group.
Department of Food Science and Technology, School of Agriculture, Nagoya University, Japan.
T
T
Sasaki
A
A
Kohara
H
H
Takagi
T
T
Shimidzu
D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx; D004591:Electrophoresis, Polyacrylamide Gel; D006458:Hemolymph; D007814:Larva; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D010447:Peptide Hydrolases / Q000378:metabolism*; D011480:Protease Inhibitors; D012689:Sequence Homology, Nucleic Acid; D000515:alpha 1-Antitrypsin / Q000378:metabolism*
D010446:Peptide Fragments; D011480:Protease Inhibitors; D000515:alpha 1-Antitrypsin; D010447:Peptide Hydrolases