Characterization of Protein Disulfide Isomerase of Conus Betulinus Linnaeus Native to Hainan

The protein disulfide isomerase(PDI) is an important foldase to fold the nascent polypeptide chain in the endoplasmic reticulum(ER).PDI is rich in the venom of tropic officinal marine cone snails and is important in facilitating the folding and maturation of secretory conopeptides in vivo.The natural PDI was prepared from the venom of Conus betulinus native to Hainan by gel-filtration chromatography and Rotofor preparative liquid-phase isoeletric focusing electrophoresis,and the purity was analyzed by SDS-PAGE and MALDI-TOF MS.Following our optimized protocol for the purification of natural Conus PDI,the catalytical activity of the obtained PDI was tested using linear conopeptide K412 as the substrate for oxidative folding.Among the complexed forms of the conopeptides following oxidative folding,only the ones with the proper disulfide bond formation exert pharmacological activities.Our preparation would be useful for the further studies on the PDI application in the oxidative folding of a great variety of conopeptides.