8I0P|1|C|MG|1501 MG ion 8I0P|1|7|ZN|201 ZN ion 8I0P|1|7|ZN|202 ZN ion 8I0P|1|7|ZN|203 ZN ion 8I0P|1|K|ZN|500 ZN ion 8I0P|1|C|GTP|1500 GTP rna