(R)-5-[(Aminoiminomethyl)amino]-2-hydroxy-pentanoic Acid-13C5 is carbon-13 labeled (R)-5-[(Aminoiminomethyl)amino]-2-hydroxy-pentanoic Acid (A612280), which can be used to synthesize Monamidocin, a fibrinogen receptor binding inhibitor produced by Streptomyces.