Cobalt chelatase Cobalt chelatase Cobalt chelatase () is an enzyme that catalyzes the chemical reaction The 4 substrates of this enzyme are ATP, hydrogenobyrinic acid a,c-diamide, Co, and HO, whereas its 4 products are ADP, phosphate, cob(II)yrinic acid a,c-diamide, and H. The aerobic cobalt chelatase (aerobic cobalamin biosynthesis pathway) consists of three subunits, CobT, CobN () and CobS (). Cobalamin (vitamin B12) can be complexed with metal via the ATP-dependent reactions (aerobic pathway) (e.g., in "Pseudomonas denitrificans") or via ATP-independent reactions (anaerobic pathway) (e.g., in "Salmonella typhimurium"). The corresponding cobalt chelatases are not homologous. However, aerobic cobalt chelatase subunits CobN and CobS
Chemical element of the four elements nor Paracelsus' view of three fundamental elements, left open the question of the number of elements. The first modern list of chemical elements was given in Antoine Lavoisier's 1789 "Elements of Chemistry", which contained thirty-three elements, including light and caloric. By 1818, Jöns Jakob Berzelius had determined atomic weights for forty-five of the forty-nine then-accepted elements. Dmitri Mendeleev had sixty-six elements in his periodic table of 1869. From Boyle until the early 20th century, an element was defined as a pure substance that could not be decomposed into any simpler substance. Put another way, a chemical