Superfamily of activating enzymes (E1) of the ubiquitin-like proteins. This family includes classical ubiquitin-activating enzymes E1, ubiquitin-like (ubl) activating enzymes and other mechanistic homologes, like MoeB, Thif1 and others. The common reaction mechanism catalyzed by MoeB, ThiF and the E1 enzymes begins with a nucleophilic attack of the C-terminal carboxylate of MoaD, ThiS and ubiquitin, respectively, on the alpha-phosphate of an ATP molecule bound at the active site of the activating enzymes, leading to the formation of a high-energy acyladenylate intermediate and subsequently to the formation of a thiocarboxylate at the C termini of MoaD and ThiS.
Jiyao W et al.(2023). "The conserved domain database in 2023.",