Researchers uncover a mechanism that may explain why biology consistently selects one molecular form over its mirror image. A new study suggests that life’s long-standing preference for one “handed” version of molecules, known as homochirality, may stem from a subtle quantum effect: electron spin. Researchers found that when electrons move through mirror-image molecules, their spin interacts differently with each form, causing small but meaningful differences in behavior during dynamic processes like chemical reactions or electron transport. Although these molecules are chemically identical in static conditions, this spin-driven asymmetry could make one version consistently more efficient over time, gradually leading to the dominance of a single “hand” in biology. The findings point to a surprising role for quantum physics in shaping the fundamental structure of life.

New analytical methods developed at Baylor College of Medicine and collaborating institutions have increased our understanding of how bacteria manage DNA. The methods enabled researchers to uncover how the sequence, physical shape and flexibility of DNA guide the activity of an enzyme called DNA gyrase, which used to get all the credit for managing DNA. Their work uncovers that certain attributes of DNA are major players in this game. The study, which appeared in Nature Communications, has implications for antibiotic design.