The Π HELIX—A HYDROGEN BONDED CONFIGURATION OF THE POLYPEPTIDE CHAIN

Low, Barbara W.; Baybutt, R. B.

doi:10.1021/ja01142a539

Cited by 74 publications

(44 citation statements)

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“…The lattice serves as a device for representing all the possible conformations of the chain backbone at low resolution by a finite countable set of configurations using fixed bond angles (27,28,30 Corey-Branson a-helix cannot be represented with perfect accuracy on any lattice of low coordination number, but the helices observed in crystallography data bases of real proteins are likewise not perfect a-helices. The identification of helices varies depending on different definitions (18,19,(31)(32)(33)(34)(35)(36)(37); in addition, some helices of different topology also occur in proteins (with low frequency), namely the 310-and ir-helices (18,(38)(39)(40). Our four representations of helices on the simple cubic lattice are described elsewhere (41).…”

Section: Lattice Approachmentioning

confidence: 99%

Origins of structure in globular proteins.

Chan

Dill

1990

Proc. Natl. Acad. Sci. U.S.A.

312

172

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The principal forces of protein foldinghydrophobicity and conformational entropy-are nonspecific.A long-standing puzzle has, therefore, been: What forces drive the formation of the specific internal architectures in globular proteins? We find that any self-avoiding flexible polymer molecule will develop large amounts of secondary structure, helices and parallel and antiparallel sheets, as it is driven to increasing compactness by any force of attraction among the chain monomers. Thus structure formation arises from the severity of steric constraints in compact polymers. This steric principle of organization can account for why short helices are stable in globular proteins, why there are parallel and antiparallel sheets in proteins, and why weakly unfolded proteins have some secondary structure. On this basis, it should be possible to construct copolymers, not necessarily using amino acids, that can collapse to maximum compactness in incompatible solvents and that should then have structural organization resembling that of proteins.What force causes the internal architectures in globular proteins? Although the dominant force of folding is the hydrophobic interaction (1) (ii) The most stable helices (21,22) are typically longer than 15 residues and are not completely helical; in contrast in globular proteins, the average helix length is 12 residues, the most common helix length is less than 6 residues (18-20), and these are 100% helical up to nearly the denaturation temperature of the protein.(iii) "Local" sequence information has been insufficient to predict protein structures (23-26). What then is the origin of the regular and irregular conformations that comprise globular proteins?Lattice Approach

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Section: Lattice Approachmentioning

confidence: 99%

Origins of structure in globular proteins.

Chan

Dill

1990

Proc. Natl. Acad. Sci. U.S.A.

312

172

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“…The a-helix, [13] the 3 10 -helix, [14] and the p-helix [15] were predicted long ago. The a-helix is the most common in peptides and proteins, the 3 10 -helix is found much less frequently in proteins, [16,17] but the p-helix is more common than usually supposed [18,19] and has been prepared on a template.…”

Section: Introductionmentioning

confidence: 99%

N‐Alkylacylamides in Thin Films Display Infrared Spectra of 3₁₀‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases

Kosower

Borz

2014

ChemPhysChem

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A peptide model is a physical system containing a CONH group, the simplest being HCONHCH3 , N-methylformamide (NMF). We have discovered that NMF and N-methylacetamide (NMA), which form hydrogen-bonded oligomers in thin films on a planar AgX fiber, display infrared (IR) spectra with peaks like those of polypeptide helices. Structures can be assigned by their amide I maxima near 1672 (3(10)), 1655 (3(10)), 1653 (α), 1655 (π), and 1635 cm(-1) (π), which are the first IR data for the π-helix. Sharp peaks are an outcome of immobilization of polar species on the polar surface of silver halides. We report the first use of expanded thin-film IR spectroscopy, in which plots of every spectrum over the amide I-II range show pauses or slow stages in the increase or decrease of absorption. These are identified as static phases followed by dynamic phases, with the incremental gain or loss of a helix turn. A general theory can be stated for such processes. Density functional calculations show that the NMA α-helix pentamer (crystal structure geometry) is transformed into a π-helix-like form. For the first time, an entire sequence (3(10)-helix, α-helix, π-helix, quasiplanar species) of spectra has been recorded for NMA.

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“…[7] If the peptide chain winds up less tightly by H-bond formation between i th CO and (i+5) th NH, the result is a π helix (φ = -55; ψ = -70), which is rare (Figure 1). [8] The contiguous arrays of H-bonds in the alpha helix give rise to a rigid rodlike structure. The right-handed helices are favored over left-handed ones in natural system due to the stereochemical nature of the amino acid monomers.…”

Section: Introductionmentioning

confidence: 99%

From Peptides to Non‐Peptide Alpha‐Helix Inducers and Mimetics

Haridas

2009

Eur J Org Chem

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Helix mimetics are good models for investigating the theories of protein folding and also act as good affinity ligands for therapeutic applications due to their biostability and better blood-brain barrier crossing ability. The helix mimetics display the same spatial and temporal orientation with respect to the amino acid side-chains of alpha helix part of the protein, which are involved in protein-protein interactions. The designed nonpeptidic molecules with substituents at the ap-

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The Π HELIX—A HYDROGEN BONDED CONFIGURATION OF THE POLYPEPTIDE CHAIN

Cited by 74 publications

References 0 publications

Origins of structure in globular proteins.

Origins of structure in globular proteins.

N‐Alkylacylamides in Thin Films Display Infrared Spectra of 3₁₀‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases

From Peptides to Non‐Peptide Alpha‐Helix Inducers and Mimetics

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The Π HELIX—A HYDROGEN BONDED CONFIGURATION OF THE POLYPEPTIDE CHAIN

Cited by 74 publications

References 0 publications

Origins of structure in globular proteins.

Origins of structure in globular proteins.

N‐Alkylacylamides in Thin Films Display Infrared Spectra of 310‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases

From Peptides to Non‐Peptide Alpha‐Helix Inducers and Mimetics

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N‐Alkylacylamides in Thin Films Display Infrared Spectra of 3₁₀‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases