Enzymatic products can change when enzymes evolve . To determine if the enzymatic product had changed in any substantial way, we compared the GRLMR and SeR enzymatic products produced with SeO3 2-substrates. GRLMR is known to produce approximately spherical red Se nanoparticles (SeNPs) whose size depends upon the initial concentration of SeO3 2-. Modifying GRLMR could potentially change product size, morphology, and allotrope of the resulting SeNPs.