Chemistry Nobel: Explaining Molecular Orientation, Elegantly

The 2023 Nobel Prize in Chemistry was awarded to two researchers for their work in understanding the molecular orientation of molecules, particularly in the context of living organisms. Henri Kagan, a 95-year-old emeritus professor at the University of Paris-Sud, and Kenso Soai, a 76-year-old emeritus professor at the Tokyo University of Science, were recognized for their groundbreaking discoveries.

Kagan's work in the early 1980s revealed that manipulating a catalyst could produce an excess of one mirror-image form of a molecule, based on its chirality or handedness. This discovery opened up new possibilities for synthesizing useful quantities of one form of the molecule in fields such as pharmaceuticals. Soai built upon Kagan's work two decades later, producing conditions where the catalyst was the molecule itself, leading to a process called autocatalysis.

This advancement had significant implications for drug development, as the proteins that drug molecules target respond differently to the two mirror images.

The importance of chirality in drug development became evident during the Thalidomide crisis in the 1950s, when a drug meant to alleviate morning sickness during pregnancy caused severe birth defects. One molecule of the drug was safe, while the other was not, due to differences in handedness. This tragedy underscored the need for careful testing of drug molecules in terms of their orientation and effects.

Kagan's work directly contributed to the development of at least one effective anti-HIV drug, Efavirenz, and the Parkinson's drug, levodopa, which contains one effective or "chiral" molecule. The phenomenon of molecular chirality is also relevant in the perfume industry, where the scent's intensity, receptivity, and quality are determined by whether it is left- or right-handed.

Interestingly, some observers believe that this year's Nobel Prize in Chemistry came late, as the concept had been anticipated as far back as a quarter of a century ago. The French science minister criticized the omission of Kagan in 2001, highlighting the significance of the work. The laureates' discovery elegantly explains why the very basis of life is homochiral, with amino acids being L-configured and sugars forming DNA and RNA being D-configured.