Ni2+-affinity chromatography of cadmium response protein in microcrustacean Moina macrocopa

Abstract

              Induction of sulfhydryl-rich protein synthesis was studied in microcrustaceans Moina macrocopa exposed to CdCl₂ at concentrations of 0 and 160 µg L^-1 for 48 h. The results implicated that sulfhydryl-rich protein increased when Moina macrocopa were exposed to cadmium. This study was successful in employing a simple one-step method to purify sulfhydryl-rich protein from microcrustaceans Moina macrocopa after exposed to cadmium by using a metal-chelating affinity chromatography. As the results, a high molecular weight sulfhydryl-rich protein of approximately 60 kDa could be purified and separated from other proteins using Ni-Sepharose column. The purified sulfhydryl-rich protein was evaluated by SDS-PAGE and further identified by MALDI-TOF-MS analysis. A striking result is the strong induction of a Spätzle protein, which is well-known for the cysteine-knot domain in its structure. This research demonstrated for the first time the existence of a Spätzle protein in the microcrustaceans Moina macrocopa in response to cadmium exposure.