Ethyl-L-NIO, the saturated analog of vinyl-L-NIO, is a modestly selective NOS inhibitor. The Ki values for inhibition of nNOS, eNOS, and iNOS by ethyl-L-NIO are 5.3, 18, and 12 μM, respectively, as determined using initial rate measurements. However when evaluating the Ki/Km ratio, ethyl-L-NIO does not show biologically significant selectivity for nNOS over eNOS, and instead favors iNOS (Ki/Km = 3.79, 5, and 0.96 μM, respectively). Although ethyl-L-NIO inhibits nNOS, it does not inactivate nNOS in the presence of NADPH and O2.
