Figure 11.

Inhibition of P5C dehydrogenase by arginine. The effect of increasing levels of arginine on the activity of the purified enzyme was determined using NAD⁺ as the electron acceptor at varying L-P5C (A) or NAD⁺ (B) concentration. Lines intersecting on the x axis account for a mechanism of non-competitive type with respect to NAD⁺ (B), with a K_I value of 88.1 ± 2.9 mM. On the contrary, parallel lines for different arginine concentrations are consistent with an inhibition of uncompetitive type with respect to P5C (A), with a K_I value of 62.3 ± 2.4 mM.