Characterizing Stability Conditions For Coiled-Coil Formation And Design
Date
2022-05
Authors
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Journal ISSN
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Publisher
University of Delaware
Abstract
In Nature, complex biopolymer molecules help form the basis for all life.
Proteins and polypeptides are made up of sequences of amino acids, which define the
structure and function of the molecule. The primary sequence specificity and its
associated assembly into higher ordered structures provides a framework for
engineering of materials. One higher ordered structure is the coiled-coil motif, which
has a variety of desired properties as a molecular building block. The coiled-coil can
be designed to be tolerant to a variety of solution conditions and can be modified with
a variety of chemical handles. Characterization of the thermodynamic properties that
underlie the coiled-coil stability is critical for understanding when and how these
motifs form and provide insight into more reliable peptide design. Here, the
temperature-dependent assembly/disassembly of peptides to form coiled coils are
assessed over a range of solution conditions using circular dichroism (CD)
spectroscopy. The effect of both salt types of different concentrations and varying pH
conditions on the coiled-coil stability was assessed. For the computationally designed
coiled-coil sequence that was selected, it was found that monovalent salts increase the
stability while multivalent salts altered the structure and increased aggregation. For pH
conditions, it was discovered that this sequence had a large range of stability along the
pH scale, which correlates with where the normal computationally designed charge
state was maintained. When (de)protonation of amino acid residues along the peptide
led to charge state changes at more extreme pH values, this led to aggregation,
precipitation, and unordered structure. This was utilized to cycle the pH for temporal
control over the coiled-coil, which was shown to be reversible. This indicates the possibility to utilize those pH stability restrictions for novel de novo peptide and
material design.
Description
Keywords
Coiled-coil, Peptides, Circular dichroism