The binding of trivalent chromium to low-molecular-weight chromium-binding substance (LMWCr) and the transfer of chromium from transferrin and chromium picolinate to LMWCr

-transferrin and the nutritional supplement chromium picolinate, Cr(pic)3, was examined. These results are consistent with the model of the mode of action of LMWCr; a Hill study indicates the four chromic ions bind to apoLMWCr in a highly cooperative fashion (n=3.47) with a binding constant of 1.54×1021. Chromium is readily transferred from transferrin to apoLMWCr at near neutral pH. The results also suggest that reduction of the chromic center of Cr(pic)3 may be required for the supplement to release chromium; thus, release of chromium is related to a mechanism by which Cr(pic)3 may generate hydroxyl radicals in cells.