A recombinant molt-inhibiting hormone of the kuruma prawn has a similar secondary structure to a native hormone: Determination of disulfide bond arrangement and measurements of circular dichroism spectra

In crustaceans, molt-inhibiting hormone (MIH) is presumed to regulate molti ng through suppressing synthesis and/or secretion of ecdysteroids by the Y- organ. Recently, a recombinant MIH of the kuruma prawn Penaeus japonicus wa s produced in E. coli. To approximate the secondary structure of native and recombinant MIH of P. japonicus containing six cysteine residues, the arra ngements of disulfide bridges in both MIHs were determined by characterizin g their enzymatic digests, and their circular dichroism spectra were measur ed. The arrangements of disulfide bonds in both MIHs were determined to be identical, and they were linked between Cys(7) and Cys(44), Cys(24) and Cys (40) and Cys(27) and Cys(53). The circular dichroism spectra of both MIHs w ere very close, and demonstrated that they were rich in alpha -helix. alpha -Helix contents in native and recombinant MIHs were calculated to be 49.3% and 46.0%, respectively. All these results strongly suggested that the rec ombinant MIH was folded in the same manner as the native MM.