Half a century of Ramachandran plots

On the occasion of their fiftieth birthday, it is opportune to
review the first half century of Ramachandran plots. In the
present review, some of the most relevant aspects of this
fifty-year history are summarized, from the original ideas of
Gopalasamudram Narayana Ramachandran to subsequent
revisions and to applications in structural biology. This will
not be a guided walk through five decades of Ramachandran
plots, but a commented summary of the lines along which the
original ideas evolved and continue to develop, and of their
applications.