Polypeptides, helical, configurations

Pauling, L., Corey, R.B., Branson, H.R. The structure of proteins two hydrogen-bonded helical configurations of the polypeptide chain. Proc. Natl. Acad. Sd. USA 37 205-211, 1951. 

Figure 3-4. Dimensions of a fully extended polypeptide chain. The four atoms of the peptide bond (colored blue) are coplanar. The unshaded atoms are the a-carbon atom, the a-hydrogen atom, and the a-R group of the particular amino acid. Free rotation can occur about the bonds that connect the a-carbon with the a-nitrogen and with the a-carbonyl carbon (blue arrows). The extended polypeptide chain is thus a semirigid structure with two-thirds of the atoms of the backbone held in a fixed planar relationship one to another. The distance between adjacent a-carbon atoms is 0.36 nm (3.6 A). The interatomic distances and bond angles, which are not equivalent, are also shown. (Redrawn and reproduced, with permission, from Pauling L, Corey LP, Branson PIR The structure of proteins Two hydrogen-bonded helical configurations of the polypeptide chain. Proc Natl Acad Sci U S A 1951 37 205.)...

Second, our studies of the secondary structure of the H" "-ATPase indicate that about 36% of the polypeptide chain is present in a helical configuration [27,42]. If the membrane-embedded sector of the molecule is helical as shown, only 90 or so additional residues in the molecule can be present as helices. Thus, the great majority... 

Pauling, L. and Corey, R. B. (1951), Atomic coordinates and structure factors for two helical configurations of polypeptide chains , Proceedings of the National Academy of Sciences (USA),... 

Figure 7 shows schematic reproductions of the shapes of the X-ray diffractive traces of alpaca observed after treatments in water and tetrachloroethylene. The reflections observed at about 9.8° (20) may indicate that the fibers contain ordered components having a specific helical configuration of the polypeptide chains (31). Aqueous treatments caused some changes in the intensities of the traces. In comparison, the nonaqueous treatment in tetrachloroethylene yielded a trace not much different from the control trace. On the basis of these observations, it is postulated that nonaqueous treatments affect the fiber morphology of historic cotton and protein fibers to a lesser degree than aqueous cleaning treatments. 

THE STRUCTURE OF PROTEINS TWO HYDROGEN-BONDED HELICAL CONFIGURATIONS OF THE POLYPEPTIDE CHAIN... 

Proposed compound helical configurations of polypeptide chains. 

L. Pauling, R. B. Corey and H. R. Branson. The structure of proteins - 2 hydrogen-bonded helical configurations of the polypeptide chain. Proceedings of theNational Academy of Sciences, USA, 37 (1951), 205. 

Donohue, J. (1953) Hydrogen bonded helical configurations of the polypeptide chain. Proe. Natl. Aead. Sci. U.S.A. 39, 470 78. 

Pauling L, R B Corey and FI R Bronson 1951 The Structure of Proteins Two Hydrogen-bonded Helical Configurations of the Polypeptide Chain Proceedings of the National Academy of Sciences USA 37 205-211... 

Polypeptides A large number of amino acid residues joined by peptide bonds. Depending on external conditions pol 7peptides may exist in a helical configuration (Fig. 7) or in a randomly coiled form (see Fig. 8 on page 7). 

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