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The Ramachandran Principle: Phi (φ) and Psi (ψ) Angles in Proteins

The Ramachandran Principle: Phi (φ) and Psi (ψ) Angles in Proteins

An interactive molecular model illustrates rotation of phi and psi angles in polypeptides, showing clashes forming and receding in real time. The Ramachandran principle is explained: The common secondary structures of alpha helices, beta strands, and turns/coil are the only conformations that are physically possible, because they avoid inter-atomic clashes. Also illustrated: the partial double-bond nature of peptide bonds and how each peptide...

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Eric Martz
Eric Martz (Faculty)
4 years ago
Shaun Lott (Univ. Auckland, New Zealand) commented in August, 2018, "A really excellent resource - the clearest visual for the concept that I’ve seen. I’ll be sending all my undergrad students to it."