Amino acids with the next chalcogen down are also found in nature: several species such as Aspergillus fumigatus, Aspergillus terreus, and Penicillium chrysogenum in the absence of sulfur are able to produce and incorporate into protein tellurocysteine and telluromethionine.
Os aminoácidos co seguinte calcóxeno tamén se atopan na natureza: varias especies de fungos como Aspergillus fumigatus, Aspergillus terreus, e Penicillium chrysogenum en ausencia de xofre poden producir e incorporar ás proteínas telurocisteína e telurometionina.