Microsomal metabolism of the Z and E isomers of N-nitroso-N-methyl-N-n-pentylamine.

N-Nitrosomethyl-N-n-pentylamine was separated into its E and Z isomers by HPLC. When the metabolism was examined using microsomes isolated from uninduced Fischer 344 rats, it was found that, at a constant final concentration of 0.5 mM, the yield of formaldehyde produced increased as the proportion of the Z isomer rose. The yield of valeraldehyde, on the other hand, decreased with an increasing proportion of the Z isomer. Kinetic constants were determined for the metabolism of the two isomers. During the metabolism of the Z isomer, the Vmax was 2.2-fold higher for the formation of formaldehyde than that for the E. The Vmax for valeraldehyde was 2.0-fold lower during the metabolism of the Z isomer. The results indicate that the relative position of the nitroso group can have a profound effect on the metabolism of each side of this type of molecule.