# NORMAL COORDINATE TREATMENT FOR POLYPEPTIDES IN VARIOUS CONFIGURATIONS

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 Title: NORMAL COORDINATE TREATMENT FOR POLYPEPTIDES IN VARIOUS CONFIGURATIONS Creators: Miyazawa, Tatsuo Issue Date: 1959 Publisher: Ohio State University Abstract: The first order perturbation theory was applied to the normal coordinate treatment for polypeptides in various configurations. The amide I and II frequencies were calculated in terms of adjacent group interactions as well as interchain and intrachain hydrogen bonding interactions. All of these interactions depend upon the configuration of polypeptide chains and also upon the chain packing in the crystal. Each characteristic vibration of the peptide group gives rise to parallel and perpendicular bans. The amide I band of the $\alpha$ helix at $1650 cm^{-1}$ is a composite of these two bands. Both the parallel-chain and antiparallel-chain pleated sheets exhibit the perpendicular amide I band at $1630 cm^{-1}$. The latter gives the parallel amide I band at $1690^{-1}$, and the former is expected to show the parallel amide I band at $1650 cm^{-1}$. Frequency differences of the amide I bands of those configurations have been explained in terms of various vibrational interaction mentioned above. The $\alpha$ helix exhibits the parallel amide II band at $1515 cm^{-1}$ and the perpendicular amide II band $1545 cm^{-1}$. Intensity comparisons of these two types of bands allow quantitative estimations of the directions of the associated transition moments of each group with respect to the fiber axis. Description: Author Institution: Children's Cancer Research Foundation, Inc. URI: http://hdl.handle.net/1811/7826 Other Identifiers: 1959-C-9