ACT_SITE 240; /note="Charge relay system"; /evidence="ECO:0000250"; ACT_SITE 372; /note="Charge relay system"; /evidence="ECO:0000250"; ACT_SITE 448; /note="Charge relay system"; /evidence="ECO:0000250"; ACT_SITE 544; /note="Proton donor"; /evidence="ECO:0000255|PROSITE-ProRule:PRU10003"