Contribution of the two domains of E. coli 5′-nucleotidase to substrate specificity and catalysis

► The N- and C-terminal domains of E. coli 5′-nucleotidase fold individually. ► Only the N-terminal domain is catalytically active in absence of the other domain. ► The N-terminal domain is responsible for the core catalytic steps. ► The C-terminal domain provides the specificity for nucleotide substrates.