ACT_SITE 712; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 846; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 922; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 1018; /note="Proton donor"; /evidence="ECO:0000255|PROSITE-ProRule:PRU10003"