Prolyl isomerization: How significant for in vivo protein folding?
✍ Scribed by Don B. Wetlaufer
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1985
- Tongue
- English
- Weight
- 329 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Synopsis
Suggestive but not decisive evidence indicates that in vivo peptide chain folding is completed in a time not much longer than that required for covalent peptide synthesis. Extrapolation of model peptide rates of the cis-tmns prolyl isomerization leads to the prediction that protein folding should be much slower than the apparent in vivo rates. On the assumption that rapid protein folding in vivo is the rule, three routes are suggested by which a protein undergoing biosynthesis can avoid a strongly slowed folding rate: (1) by a peptide chain-elongation process that adds only tmns peptide bonds, followed by a rapid folding process that incorporates them into a three-dimensional structure, raising the energy barrier to isomerization; (2) by folding to produce threedimensional structures that position prolyl residues largely in chain turns on the protein surface, where the residue may be either cis or tmns without large effects on the protein structure and function; (3) prolyl cis-tmns isomerization may be speeded by the formation of peptide loops.