Agmatine oxidation by copper amine oxidase -: Biosynthesis and biochemical characterization of N-amidino-2-hydroxypyrrolidine

The product of agmatine oxidation catalyzed by Pisum sativum L. copper amine oxidase has been identified by means of one- and two-dimensional H-1-NMR spectroscopy to be N-amidino-2-hydroxypyrrolidine. This compound inhibits competitively rat nitric oxide synthase type I and type II (NOS-I and NOS-II, respectively) and bovine trypsin (trypsin) activity, values of K-1 being (1.1 +/- 0.1) x 10(-5) M (at pH 7.5 and 37.0 degreesC), (2.1 +/- 0.1) x 10-(5) M (at pH 7.5 and 37.0 degreesC). and (8.9 +/- 0.4) x 10(-5) M (at pH 6.8 and 2 1.0 degreesC), respectively. Remarkably, the affinity of N-amidino-2-hydroxypyrrolidine for NOS-I, NOS-II and trypsin is significantly higher than that observed for agmatine and clonidine binding. Furthermore, N-amidino-2-hydroxypyrrolidine and agmatine are more efficient than clonidine in displacing [H-3]clonidine (= 1.0 x 10(-8) M) from specific binding sites in heart rat membranes, values of IC50 being (1.3 +/- 0.4) x 10(-9) M and (2.2 +/- 0.4) x 10(-8) M, respectively (at pH 7.4 and 37.0 degreesC).