β Scribed by Hirotoshi Ito; Toshiyuki Eri; Y.J. I'haya
No coin nor oath required. For personal study only.
The linear response theory of configurationally induced opticai rotation for heIicaI biopolymers is formulated in terms of the molecular polarizability. Simple numerical computation of the ORD and the CD curves is carried out for the singlestranded polyadenylic acid hating the configuration of DNA.
Recently, molecular polarizability theories have received considerable attention for describing certain electronic spectral properties [l-lo].
Concerning optical rotation especially, Kirkwood [l] has presented a polarizability theory which was improved by Moffiit et al. [3_,3] and extensively applied to polymer systems by Tinoco et aI. [4]. Such studies, as subsequently exploited, were concerned with molecular orbital theories based upon Kirkwood's assumption that the electrons in a molecule are localized in particular groups which only interact through the eldctric field. In parallel with this approach, the Fano-DeVoe mode1 [5,6j for describing co!lective excitations and intensities, which classically treats a polymer as an assembly of coupled harmorric oscillators, was extended to the optical rotatory dispersion (ORD) theory by McLacNan and Ball [ 1 I ] and later by DeVoe [ 121. Also, the idea of the Fano-DeVoe mode! can be represented in terms of Green's functions which are much more flexible in use [7-lOI_ Applequist [ 131 has'derived an expression for the optical rot&on in terms of a linear response function of the polarizability, which we can either calculate just as in this perturbation method, or quantum-mechanically define (from the Green's function for the fluctuation density operator of electrons) as in the present paper. His formulation is actually a semi-classical version of the Fano-DeVoe model.
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A series of CD measurements were carried out on members of peptides in the endothelin and sarafotoxin families. The helical structures taken by these peptides containing the helical motif with the sequences of Cys-X-X-X-Cys and Cys-X-Cys [ Y. Kobayashi et al. ( 1991) Neurochemistry International Vo