1.4.1.7 additional information the enzyme has an N-terminal Rossmann fold domain connected by a long alpha-helix to the C-terminal all-alpha domain. Critical role of four amino acid residues in catalysis including the primary catalytic residue Lys171, PA0743 substrate-binding site structure, and molecular mechanisms of substrate selectivity, overview. The structure of the PA0743-NAD+ complex demonstrates that the opposite side of the enzyme active site accommodates the cofactor, which is also bound near Lys171, with dinucleotide cofactor binding GLGXMG motif-1, substrate binding DAPVSGG motif-2, catalysis GXXGXGXXXKXXN motif-3, and cofactor binding motif-4 725474