Homocysteine and methionine are key amino acids with a vital connection to glutathione one of your body's most important substances! Methionine is abundant in many foods, so protein isn't the culprit, Glutathione S Transferase (GST) Fusion Based Assays for Studying Protein Protein Interactions Springer Nature Link High Homocysteine Linus Pauling Institute Oregon State University Full article: Tetraspanin decorated extracellular vesicle mimetics as a novel adaptable reference material