6ZXF|1|z|MG|601 MG ion 6ZXF|1|z|MG|602 MG ion 6ZXF|1|d|ZN|101 ZN ion 6ZXF|1|f|ZN|500 ZN ion 6ZXF|1|y|ZN|500 ZN ion 6ZXF|1|z|ATP|603 ATP rna