preferred_name: a 2'-deoxyribonucleoside + a ribonucleoside 5'-phosphate <=> a ribonucleoside + a 2'-deoxyribonucleoside 5'-phosphate
preferred_name_lc: a 2'-deoxyribonucleoside + a ribonucleoside 5'-phosphate <=> a ribonucleoside + a 2'-deoxyribonucleoside 5'-phosphate
label: a 2'-deoxyribonucleoside + a ribonucleoside 5'-phosphate <=> a ribonucleoside + a 2'-deoxyribonucleoside 5'-phosphate
label_lc: a 2'-deoxyribonucleoside + a ribonucleoside 5'-phosphate <=> a ribonucleoside + a 2'-deoxyribonucleoside 5'-phosphate