Our motivation for altering metal(loid) reductase substrate specificity is driven by our interest in producing cloneable nanoparticles of distinct size/shape/elemental composition . A cloneable inorganic nanoparticle is synthesized in physiological conditions, has well-defined elemental composition, size, shape, and crystal structure. Because the protein determines these nanoparticle properties, and proteins are encoded in DNA, the properties of the nanoparticle are encoded in DNA.