pauling and corey's studies of the peptide bond showed that Pauling, Corey, and Branson took the planar peptide bond to be reliable - Themajor reasonthatantiparallel b strands at pH 7, many different peptide bond conformations are equally probable

Thesecondary structure shown below is an exampleofa n ): Linus Pauling and Robert Corey's groundbreaking studies of the peptide bond in the early 1950s revealed fundamental insights into protein structureThe discovery of the alpha-helix and beta-sheet .... Their X-ray diffraction analyses of crystalline peptides demonstrated that the peptide bond is essentially planar, a crucial characteristic that significantly restricts the possible conformations of polypeptide chains. This planarity arises from the partial double-bond character of the C-N bond due to resonance, meaning that all atoms involved in the peptide linkage—the carbonyl carbon, the carbonyl oxygen, the amide nitrogen, and the amide hydrogen—lie in the same plane.The discovery of the alpha-helix and beta-sheet ...

The Planar Nature of the Peptide Bond

The most significant finding from Pauling and Corey's work was the planarity of the peptide bond. This geometric constraint means that there is restricted rotation around the C-N bond. Instead, rotation occurs around the bonds adjacent to the peptide bond: the N-Cα bond and the Cα-C bond. This limited rotation dictates the backbone arrangements possible for proteins, forming the basis for secondary structures like alpha helices and beta sheetsProtein Folding: Part I—Basic Principles. The resonance stabilization gives the C-N bond some double-bond character, preventing free rotation and locking the atoms into a planar configuration.

Implications for Protein Conformation

The planar nature of the peptide bond has profound implications for how proteins fold and adopt their three-dimensional structures. Because rotation is restricted to two specific bonds in each amino acid residue, the polypeptide chain can only adopt a limited number of specific spatial arrangements11. Corey - Linus Pauling and the Structure of Proteins. Pauling and Corey's studies were instrumental in predicting and understanding these arrangements, leading to the proposal of the alpha-helix and beta-sheet as fundamental protein secondary structures. These structures are stabilized by hydrogen bonds between the carbonyl oxygen of one peptide bond and the amide hydrogen of another, with the specific geometry dictated by the planar peptide units作者：GD Chellapa·2015·被引用次数：9—Pauling'smastery ofpeptidestereochemistry-based on small molecule crystal structures and the theory of chemicalbonding-led to his realization that the ....

Limited Rotation and Conformation Probabilities

While the peptide bond itself is planar and does not rotate, the surrounding bonds (N-Cα and Cα-C) allow for rotation. This rotation is often described by the dihedral angles phi (φ) and psi (ψ). Pauling and Corey's work, along with subsequent research, indicated that at physiological pH, many different peptide bond conformations are not equally probable.2024年2月19日—Pauling and Corey's studies of the peptide bond showed that: A)at pH 7, many different peptide bond conformations are equally probable. B) ... Instead, specific angles of rotation are favored due to steric hindrance and the ability to form stabilizing hydrogen bonds, leading to the formation of regular secondary structures. The resonance also influences the bond lengths, making the C-N bond intermediate between a single and a double bond.

Conclusion

Pauling and Corey's studies of the peptide bond were a pivotal moment in understanding protein structureProperties of the Peptide Bond In x-ray studies .... Their confirmation of the peptide bond's planarity and the associated limited rotation around adjacent bonds provided the essential framework for understanding protein secondary structures.Which of the following best represents the backbone arrangement of two ... These foundational findings continue to be critical in fields ranging from biochemistry and molecular biology to drug design and structural bioinformatics作者：D Eisenberg·2003·被引用次数：408—Paulinghad predicted planarpeptidegroups because of resonance of electrons between the doublebond...Pauling and Coreysubmitted their seven protein ....