BEC

L-Arginine serves as a common substrate for both NOS and arginase in the cell. NOS catalyzes the oxidation of arginine to citrulline and NO with N.omega.-hydroxy-L-arginine (NOHA) formed as an intermediate. Arginase, on the other hand, catalyzes the hydrolysis of arginine into urea and L-ornithine. BEC is a potent slow-binding competitive inhibitor of recombinant rat liver arginase I with a Ki of 0.4-0.6 µM.{13099} It is also a potent inhibitor of human arginase II with Ki values of 0.31 µM and 30 nM at pH 7.5 and 9.5, respectively.{13124} It does not inhibit murine iNOS at concentrations up to 1 mM. BEC significantly enhances NO-dependent relaxation of human penile corpus canvernosum smooth muscle in vitro at concentrations between 0.1-1.0 mM.{13099}