ACT_SITE 142; /evidence="ECO:0000250|UniProtKB:P27695"; ACT_SITE 183; /note="Proton donor/acceptor"; /evidence="ECO:0000269|PubMed:32516598"; ACT_SITE 300; /note="Proton acceptor"; /evidence="ECO:0000255|PROSITE-ProRule:PRU00764"