ACT_SITE 319; /note="Thioimidate intermediate"; /evidence="ECO:0000255|HAMAP-Rule:MF_03156, ECO:0000269|PubMed:12235158, ECO:0000269|PubMed:12549902"; ACT_SITE 418; /note="Proton acceptor"; /evidence="ECO:0000255|HAMAP-Rule:MF_03156"