Figure 3.

Structures of the active sites in the α^Mgγ^Mg+CIT+ATP and α^Mg+ATPγ^Mg+CIT+ATP structures. (a) Comparison of the active sites in the α^Mgγ^Mg+CIT+ATP, α^Mg+ATPγ^Mg+CIT+ATP, α^Mgγ, α^Mgγ^Mg+CIT+ADP, and α^Mg+NADHγ^NADH structures. The key residues of the active site in the α^Mgγ^Mg+CIT+ATP and α^Mg+ATPγ^Mg+CIT+ATP structures assume very similar conformations as those in the active α^Mgγ^Mg+CIT+ADP structure rather than the inactive α^Mgγ structure. The color scheme of the structures is shown above. (b) Comparison of the NAD binding sites in the α^Mg+ATPγ^Mg+CIT+ATP and α^Mg+NADHγ^NADH structures. The key residues of the NAD binding site in the α^Mg+ATPγ^Mg+CIT+ATP structure assume very similar conformations as those in the α^Mg+NADHγ^NADH structure. (c) Structure of the NAD binding site in the α^Mg+ATPγ^Mg+CIT+ATP structure. (d) Structure of the NAD binding site in the α^Mg+NADHγ^NADH structure. The key residues and the ATP (or NADH) are shown with ball-and-stick models, and the water molecule is shown with a red sphere. Hydrogen-bonding interactions of ATP (or NADH) with the surrounding residues are indicated with dotted lines.