Patchwork-structure serpins from silkworm (Bombyx mori) larval hemolymph.
A new serpin (serine proteinase inhibitor), having antichymotryptic activity, was isolated from silkworm, Bombyx mori, larval hemolymph and was named silkworm antichymotrypsin II (sw-AchyII). Amino-acid-sequence analysis of sw-AchyII revealed that it consisted of 375 amino acids without cysteine or glycosylated residues. sw-AchyII formed an SDS-undissociable complex with alpha-chymotrypsin, but this complex was broken down at pH 12.5 into alpha-chymotrypsin and sw-AchyII in which the reactive site was cleaved. Amino-acid-sequence analysis after cleavage identified in P1-P1' residue at the reactive site of sw-AchyII as Phe340-Met341. The amino acid sequence from the amino terminus to residue 336 was completely identical to the corresponding region of sw-AT [Takagi, H., Narumi, H., Nakamura, K. & Sasaki, T. (1990) J. Biochem. (Tokyo) 108, 372-378]. The degree of similarity between sw-AchyII and silkworm antitrypsin (sw-AT) from residue 337 to the carboxy terminus was only 46%. Reactive sites of both serpins were in the variable regions.
Sasaki
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Department of Food Science and Technology, School of Agriculture, Nagoya University, Aichi, Japan.
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D012831:Bombyx / Q000201:enzymology*; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006458:Hemolymph / Q000201:enzymology; D007814:Larva / Q000201:enzymology; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D015843:Serpins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
D015843:Serpins; C072138:antichymotrypsin II