Taking Turns

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Science  20 Jul 2001:
Vol. 293, Issue 5529, pp. 395-397
DOI: 10.1126/science.293.5529.395e

How do proteins fold into the correct structure—the native state—within a biologically realistic time? According to current understanding, folding occurs on a funnel-shaped free energy surface that is biased toward the native state. Along this funnel, many folding pathways are possible, but the dominant ones are believed to maximize the formation of energetically favorable native contacts while minimizing the loss in configurational entropy as the chain becomes more constrained. To test this view, Nauli et al. have redesigned a small protein so that it folds along a different pathway than the wild-type molecule. Protein G is a small protein that contains an α helix and a four-stranded β sheet formed by two β turns. The authors reordered the stability of these β turns and succeeded in inverting the sequence in which these substructures appear in the folding pathway, supporting the idea that protein folding takes the route with the most favorable interactions. — JU

Nature Struct. Biol.8, 602 (2001).

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