ACT_SITE 265; /note="Charge relay system"; /evidence="ECO:0000250"; ACT_SITE 397; /note="Charge relay system"; /evidence="ECO:0000250"; ACT_SITE 473; /note="Charge relay system"; /evidence="ECO:0000250"; ACT_SITE 571; /note="Proton donor"; /evidence="ECO:0000255|PROSITE-ProRule:PRU10003"