(TYPE OF REACTIONS) 1 Chemicals can exchange electrons to oxidize or reduce other molecules, leading to formation of harmful byproducts. For example, chemicals can oxidize Fe(II) in hemoglobin to Fe(III), producing __ 2 A few toxins ACT ENZYMATICALLY on specific target proteins. For example, __ BLOCKS THE FUNCTION OF ELONGATION FACTOR 2 in protein synthesis. 3 __ ACTIVATES A G PROTEIN through such a mechanism. 4 MOST ULTIMATE TOXICANTS act on endogenous molecules on the basis of their __