Nearly all enzymes that require a nicotinamide cofactor use either NAD⁺/NADH or NADP⁺/NADPH (Figure 11-3) but not both. Compare the net charge of each cofactor.
a) NAD⁺ has a net positive charge, NADP⁺ has a net negative charge
b) NAD⁺ has a net negative charge, NADP⁺ has a net positive charge
c) Both NAD⁺ and NADP⁺ have a net positive charge
d) Both NAD⁺ and NADP⁺ have a net negative charge