One relatively unexplored area is in enzymes that synthesize inorganic nanomaterials. Naturally occurring examples of such enzymes are common. For example, multimeric iron-storing ferritin and ferritinlike proteins oxidize soluble and highly bioavailable Fe 2+ into uniform ferric nanoparticles as a means of promoting cellular Fe 2+ homeomostasis . Multicopper oxidases such as manganese oxidase are thought to play primary roles in the bacterial formation of geological manganese oxide materials . Enzymes involved in the metabolization/release of sulfur compounds such as cystathionine-y-lyase are implicated in several biosynthetic routes to quantum dots (QDs), the compositions of which include cadmium sulfides . In our previous work, a glutathione reductase-like metalloid reductase (GRLMR) discovered in selenium tolerant microorganisms generated amorphous selenium nanoparticles in the presence of ionic selenium precursors such as SeO3 2-(selenite) and selenodiglutathione (GS-Se-SG) .