ACT_SITE 714; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 848; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 924; /note="Charge relay system"; /evidence="ECO:0000250|UniProtKB:P04035"; ACT_SITE 1020; /note="Proton donor"; /evidence="ECO:0000255|PROSITE-ProRule:PRU10003"