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Agmatine oxidation by copper amine oxidase: Biosynthesis and biochemical characterization of N‐amidino‐2‐hydroxypyrrolidine
- Ascenzi, Paolo, Fasano, Mauro, Marino, Maria, Venturini, Giorgio, Federico, Rodolfo
- European journal of biochemistry 2002 v.269 no.3 pp. 884-892
- Pisum sativum, agmatine, binding sites, biosynthesis, cattle, clonidine, heart, inhibitory concentration 50, neuronal nitric oxide synthase, oxidation, pH, rats, spectroscopy, trypsin
- The product of agmatine oxidation catalyzed by Pisum sativum L. copper amine oxidase has been identified by means of one‐ and two‐dimensional 1H‐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 Ki being (1.1 ± 0.1) × 10−5 m (at pH 7.5 and 37.0 °C), (2.1 ± 0.1) × 10−5 m (at pH 7.5 and 37.0 °C), and (8.9 ± 0.4) × 10−5 m (at pH 6.8 and 21.0 °C), 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 [3H]clonidine (= 1.0 × 10−8 m) from specific binding sites in heart rat membranes, values of IC50 being (1.3 ± 0.4) × 10−9 m and (2.2 ± 0.4) × 10−8 m, respectively (at pH 7.4 and 37.0 °C).