TY - JOUR

T1 - Characterization of dry globular proteins and protein fibrils by synchrotron radiation vacuum UV circular dichroism

AU - Nesgaard, Lise W.

AU - Hoffmann, Søren Vrønning

AU - Andersen, Christian Beyschau

AU - Malmendal, Anders

AU - Otzen, Daniel

PY - 2008/9/1

Y1 - 2008/9/1

N2 - Circular dichroism using synchrotron radiation (SRCD) can extend the spectral range down to approximately 130 nm for dry proteins, potentially providing new structural information. Using a selection of dried model proteins, including alpha-helical, beta-sheet, and mixed-structure proteins, we observe a low-wavelength band in the range 130-160 nm, whose intensity and peak position is sensitive to the secondary structure of the protein and may also reflect changes in super-secondary structure. This band has previously been observed for peptides but not for globular proteins, and is compatible with previously published theoretical calculations related to pi-orbital transitions. We also show that drying does not lead to large changes in the secondary structure and does not induce orientational artifacts. In combination with principal component analysis, our SRCD data allow us to distinguish between two different types of protein fibrils, highlighting that bona fide fibrils formed by lysozyme are structurally more similar to the nonclassical fibrillar aggregates formed by the SerADan peptide than with the amyloid formed by alpha-synuclein. Thus, despite the lack of direct structural conclusions, a comprehensive SRCD-based database of dried protein spectra may provide a useful method to differentiate between various types of supersecondary structure and aggregated protein species.

AB - Circular dichroism using synchrotron radiation (SRCD) can extend the spectral range down to approximately 130 nm for dry proteins, potentially providing new structural information. Using a selection of dried model proteins, including alpha-helical, beta-sheet, and mixed-structure proteins, we observe a low-wavelength band in the range 130-160 nm, whose intensity and peak position is sensitive to the secondary structure of the protein and may also reflect changes in super-secondary structure. This band has previously been observed for peptides but not for globular proteins, and is compatible with previously published theoretical calculations related to pi-orbital transitions. We also show that drying does not lead to large changes in the secondary structure and does not induce orientational artifacts. In combination with principal component analysis, our SRCD data allow us to distinguish between two different types of protein fibrils, highlighting that bona fide fibrils formed by lysozyme are structurally more similar to the nonclassical fibrillar aggregates formed by the SerADan peptide than with the amyloid formed by alpha-synuclein. Thus, despite the lack of direct structural conclusions, a comprehensive SRCD-based database of dried protein spectra may provide a useful method to differentiate between various types of supersecondary structure and aggregated protein species.

KW - Amino Acid Motifs

KW - Animals

KW - Circular Dichroism

KW - Humans

KW - Protein Structure, Tertiary

KW - Proteins

KW - Synchrotrons

U2 - 10.1002/bip.21011

DO - 10.1002/bip.21011

M3 - Journal article

C2 - 18459170

VL - 89

SP - 779

EP - 795

JO - Biopolymers

JF - Biopolymers

SN - 0006-3525

IS - 9

ER -