<qa>  What is the name of the enzyme arginine deiminase?The enzyme arginine deiminase ADI metabolizes arginine into citrulline Cunin 1986. However, ADI is only found in microbes and not in humans. ADI is therefore, highly immunogenic and has a short serum half-life following injection. These potential drawbacks microbial source and thus viewed as foreign by the human immune system, and a short serum half-life can be overcome by covalent attachment of polyethylene glycol PEG to argininedeiminase and termed this drug ADI-PEG 20. 