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| The rippled beta sheet is a variation on the pleated beta sheet, a well-known structural motif found in thousands of proteins. Linus Pauling and Robert Corey described the rippled beta sheet in 1953, but it remained a largely theoretical structure for decades. Scientists have now created rippled sheets in the laboratory and characterized the structure using x-ray crystallography. Credit: J. Raskatov |
An unusual protein structure known as a "rippled beta sheet," first
predicted in 1953, has now been created in the laboratory and characterized
in detail using X-ray crystallography.
The new findings, published in July in Chemical Science, may enable the
rational design of unique materials based on the rippled sheet architecture.
"Our study establishes the rippled beta sheet layer configuration as a motif
with general features and opens the road to structure-based design of unique
molecular architectures, with potential for materials development and
biomedical applications," said Jevgenij Raskatov, associate professor of
chemistry and biochemistry at UC Santa Cruz and corresponding author of the
paper.
Proteins come in an enormous range of shapes and sizes to carry out their
myriad structural and functional roles in living cells. Certain common
structural motifs, such as the alpha helix, are found in many protein
structures.
The rippled sheet is a variation on the pleated beta sheet, a well-known
structural motif found in thousands of proteins. Linus Pauling and Robert
Corey described the rippled beta sheet in 1953, two years after introducing
the concept of the pleated beta sheet. While the pleated beta sheet is well
known and often called simply the beta sheet, the rippled sheet remained a
largely theoretical structure for decades.
In a previous study published in Chemical Science in 2021, Raskatov's team
reported obtaining a rippled beta sheet structure by mixing a small peptide
with equal amounts of its mirror image. The researchers used mirror-image
forms of triphenylalanine, a short peptide consisting of three phenylalanine
amino acids. The mirror-image peptides joined in pairs to form "dimers" with
the predicted structure, but they did not form the extended, periodic
rippled beta-sheet layer topography hypothesized by Pauling and Corey.
"The dimers packed together into herringbone layer structures, which raised
doubt as to whether the periodic rippled beta-sheet layer configuration was
viable," Raskatov said.
In the new study, the researchers substituted other amino acids for one of
the triphenylalanines to create slightly different tripeptides and their
mirror-images. Using these new tripeptides, they were able to create three
different aggregating peptide systems that formed extended antiparallel
rippled beta sheet layers, in which mirror-image peptide strands were
arranged in alternating fashion. The results of X-ray crystallography showed
that the crystal structures are in excellent overall agreement with the
predictions made by Pauling and Corey.
Reference:
Amaruka Hazari et al, The rippled β-sheet layer configuration—a novel
supramolecular architecture based on predictions by Pauling and Corey,
Chemical Science (2022).
DOI: 10.1039/d2sc02531k
Ariel J. Kuhn et al, A crystal-structural study of Pauling–Corey rippled
sheets, Chemical Science (2021).
DOI: 10.1039/D1SC05731F
Tags:
Chemistry