Methionine (Met) is a common amino acid found in almost all proteins. When it undergoes oxidation (a common process in aging and disease), it transforms into methionine sulfoxide (Met-SO).The challenge is that this chemical reaction creates a new chiral center at the sulfur atom. This means that for every oxidized methionine, two different mirror-image versions (diastereomers) can exist: The (S,S) form and the (S,R) form.Before this invention, researchers struggled to separate these two forms. This resulted in two major technical hurdles:Standard techniques like High Performance Liquid Chromatography (HPLC) or fractional crystallization (a method dating back to 1947) were unreliable, difficult to reproduce, and failed to produce high-purity samplesBecause the two forms were so difficult to separate, almost all previous research on methionine oxidation used a mixture of both. This meant that if one form was toxic and the other was harmless, the results would be averaged out, hiding the true biological mechanism.A core motivation for this invention is the "staggering degree of disagreement" in Alzheimer's Disease research regarding the protein Amyloid beta (Aβ42)Some studies claimed that oxidized Aβ42 increased brain plaque toxicity, while others claimed it decreased itIt is plausible that these contradictions exist because previous researchers didn't know which specific diastereomer—(S,S) or (S,R)—they were testinOnce these two forms are created, they are remarkably stable. The energy barrier to flip from one form to the other is roughly 45.2 kcal/mol, which is significantly higher than other enantiomeric structures. This means that in the human body, the "wrong" version won't just flip back to the "right" one; it stays in that specific shape, potentially causing long-term damage if not properly regulated by specific enzymes (reductases).