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 Chemical element A chemical element is a species of atoms having the same number of protons in their atomic nuclei (that is, the same atomic number, or "Z"). For example, the atomic number of oxygen is 8, so the element oxygen consists of all atoms which have exactly 8 protons. 118 elements have been identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radionuclides, which decay over time into other elements. Iron is the most abundant