The planar conformation of a strained proline ring: A QM/MM study

@article{Donnini2006ThePC,
  title={The planar conformation of a strained proline ring: A QM/MM study},
  author={Serena Donnini and Gerrit Groenhof and Rik K. Wierenga and Andr{\'e} H. Juffer},
  journal={Proteins: Structure},
  year={2006},
  volume={64}
}
QM and QM/MM energy calculations have been carried out on an atomic resolution structure of liganded triosephosphate isomerase (TIM) that has an active site proline (Pro168) in a planar conformation. The origin of the planarity of this proline has been identified. Steric interactions between the atoms of the proline ring and a tyrosine ring (Tyr166) on one side of the proline prevent the ring from adopting the up pucker (χ1 is approximately −30°), while the side chain of a nearby alanine… 
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