biostudies-literatureMondal SUniversity of Texas at El PasoEuropean Research CouncilIsrael Science FoundationTel Aviv UniversityDivision of Materials ResearchNIGMS NIH HHSNIH HHS363-369https://www.ebi.ac.uk/biostudies/studies/S-EPMC7616934biostudies-literatureUnknown141(1)The ensemble of native, folded state was once considered to represent the global energy minimum of a given protein sequence. More recently, the discovery of the cross-β amyloid state revealed that deeper energy minima exist, often associated with pathogenic, fibrillar deposits, when the concentration of proteins reaches a critical value. Fortunately, a sizable energy barrier impedes the conversion from native to pathogenic states. However, little is known about the structure of the related transition state. In addition, there are indications of polymorphism in the amyloidogenic process. Here, we report the first evidence of the conversion of metastable cross-α-helical crystals to thermodynamically stable cross-β-sheet-like fibrils by a de novo designed heptapeptide. Furthermore, for the fiJournal of the American Chemical SocietyTransition of Metastable Cross-α Crystals into Cross-β Fibrils by β-Turn Flipping.PMC7616934550/15694426S10 OD021527P41 GM103403DMR-1506886Rehak PBeck RVukovic LMondal SSawaya MRAdler-Abramovich LShimon LJWGazit EJacoby GArnon ZAKral PfalseTransition of Metastable Cross-α Crystals into Cross-β Fibrils by β-Turn Flipping.The ensemble of native, folded state was once considered to represent the global energy minimum of a given protein sequence. More recently, the discovery of the cross-β amyloid state revealed that deeper energy minima exist, often associated with pathogenic, fibrillar deposits, when the concentration of proteins reaches a critical value. Fortunately, a sizable energy barrier impedes the conversion from native to pathogenic states. However, little is known about the structure of the related transition state. In addition, there are indications of polymorphism in the amyloidogenic process. Here, we report the first evidence of the conversion of metastable cross-α-helical crystals to thermodynamically stable cross-β-sheet-like fibrils by a de novo designed heptapeptide. Furthermore, for the fi2019-01-01T00:00:00Z2019 Jan2026-04-08T19:27:32.99Z2025-04-04T02:34:03.653ZS-EPMC76169343053295510.1021/jacs.8b10289