Folding of protein fragments.

Publisher Summary Folding of proteins to native-like structure has been demonstrated with fragments of 8-galactosidase, lysozyme, serum albumin, penicillinase, and tryptophan synthetase. The capability of protein fragments for independent formation of structure has substantial experimental basis. Protein folding occurs “by parts”—that is, in a modular fashion. The structural feature of chain continuity within a compact domain is realized in the fragments of only two of the systems in which independent folding has been shown. These two are lysozyme and thermolysin. Most of the proteins on which fragment folding studies have been carried out are extracellular. Many secreted proteins are synthesized with 20 or so additional amino acid residues at the N-terminus of the peptide chain. Secretion can impose additional constraints on protein folding. Different parts of protein molecules can form native-like structure independently. Some protein fragments show the ability to form native-like structures in vivo . So, protein folding “by parts” is a process that goes on in real life as well as in vitro . The chapter also outlines the experimental findings, protein by protein, roughly in chronological order, and explains the significance of these findings.