Is it possible to isolate and analyse intermediates of protein folding?
Theoretically by molecular modeling -- see the works by Harold Scheraga: 
https://www.ncbi.nlm.nih.gov/pubmed/?term=Harold+Scheraga%5BAuthor%5D



Note: An unfolded protein is not a random coil.

Fitzkee &amp; Rose (2004) PNAS 101:12497-12502; emphasis mine:


  denatured proteins are biased toward specific conformations, in
  ... conflict with the random-coil model


https://www.ncbi.nlm.nih.gov/pubmed/15314216