Construction of a ferritin reactor: An efficient means for trapping various heavy metal ions in flowing seawater

An apparatus consisting of two pumps, a mixer, a ferritin reactor, and a spectrophotometer was constructed to study the ability to trap various heavy metal ions (M2+) and the dynamics of a reconstituted ferritin reactor in flowing seawater. Reconstituted pig spleen ferritin (PSFr) is assembled from ape-protein shell to form a reconstituted iron core. The main components of the PSF, are its core, which contains an Fe2+:P-i stoichiometry of 6.0+/-0.5, reconstituted from pig spleen apoferritin (apo PSF), Fe2+, inorganic phosphate (P-i), and O-2 (0.6 atm). The Fe3+-P-i clusters within the PSFr core exhibit resistance to salt ranging from 1% to 6% NaCl. The ferritin reactor consists of PSFr and an oscillating bag. Using the reactor, M2+ ions such as Cd2+, Zn2+, Co2+, and Mn2+ are directly trapped by the ferritin. We found a 1:2+/-0.2 stoichiometry of the trapped M2+ to the released iron as measured by chemical analysis or atomic absorption spectrometry; nontransient elements such as Na+, K+, Ca2+, etc., were scarcely trapped by the reactor. This study provides basic conditions for establishing a ferritin reactor and a convenient means for monitoring the pollution of heavy metal ions in seawater.