text: One structural consequence of acyclic systems due to the stereoelectronic effect is the gauche effect. In 1,2-difluoroethane, despite the steric clash, the preferred conformation is the gauche one because σ(C–H) is a good donor and σ*(C–F) is a good acceptor and the stereoelectronic effect (σ(C–H) → σ*(C–F)) requires the energy minimum to be gauche instead of anti.
  This gauche effect and its impact on conformation are important in biochemistry. For example, in HIF-α subunit fragments containing (2S,4R)-4-hydroxyproline, the gauche interaction favors the conformer that can bind to the active site of pVHL. pVHL mediates the proteasomal degradation of HIF1A and with that the physiological response to hypoxia.