ACT_SITE 103; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 236; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 312; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 408; /note="Proton donor"; /evidence="ECO:0000255|PROSITE-ProRule:PRU10003"