Methionine sulfoximine inhibits both glutamine synthetase and g-glutamylcysteine synthetase. Working concentrations for inhibition of g-glutamylcysteine synthetase are 0.2-2.0 mM (52% inhibition occured at 100 mM). Methionine sulfoximine is also a toxic byproduct of nitrogen trichloride, a compound that was used to bleach unprocessed wheat flour prior to 1968. The compound has been investigated as a potential neurotoxin linked to diseases such as amyotrophic lateral sclerosis (ALS) and Parkinson’s disease.