Circular dichroism calculation for random‐coil polypeptide chains

Зубков, В. И.; Birshtein, T.M.; Milevskaya, I.S.; Volkenstein, M.V.

doi:10.1002/bip.360101102

Cited by 38 publications

(19 citation statements)

References 18 publications

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“…It thus seemed amply appropriate to revise the early assignment (15] of the CD spectrum of the maximally unordered polypeptide chain. Theoretical calculations of the CD spectrum of unordered polypeptide chains have not yielded identical results [23][24][25][26], yet in at least one calculation [26] there is consistency with such a revised assignment.…”

Section: Introductionmentioning

confidence: 99%

The Circular Dichroism Spectrum and Structure of Unordered Polypeptides and Proteins

Krimm

Tiffany

1974

Israel Journal of Chemistry

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Section: Introductionmentioning

confidence: 99%

The Circular Dichroism Spectrum and Structure of Unordered Polypeptides and Proteins

Krimm

Tiffany

1974

Israel Journal of Chemistry

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“…They were designated by Zubkov, et al 9 as a1(80° : <: : : : \D :<:::: 140°, 100° :<:::: \D :<:::: 140°), f32(0° :<:::: sa:<::::120°, -90°:<;:¢:<;:0°), f3s(30°:ssa:<::::90°, -90°:<;: ¢:<;:-30°), 1(0° :S\D:S 150°, -210° :<::::¢:<;:0°), and 2(0°:ssa:<::::120°, -60°:<;:¢:<;:0°), and each of these was assumed to be a rectangular well. Angles were taken at 10° intervals.…”

Section: Theory and Methodsmentioning

confidence: 99%

“…Our method of calculation was similar to that by Zubkov, et al 9 We adopted the regions of rotational angles <p and ¢ which Zubkov, et al used for the calculation of the amide 11:-11:* CD of random-coil polypeptide. It may be noted that the visible CD of dye-random-coil polymer complex is very sensitive to the selection of the region, while the amide r:-;r* CD changes only in the magnitude at every region, even when the selected region differs.…”

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confidence: 99%

Calculated Circular Dichroism of Acridine Orange Bound to Random-Coil Polypeptide

Imae

1977

Polym J

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ABSTRACT:A theory of circular dichroism for the amide transition of polypeptide in random-coil conformation has been developed on the basis of the exciton theory of optical activity and the Monte-Carlo approach to the treatment of statistical systems. This theory has further been extended in such a way as to be applicable for electronic transitions of chromophores bound to the side chains of the random-coil polypeptides. Circular dichroism is calculated for some binding models of acridine orange-randomcoil polypeptide complexes. The results are compared with those observed, and it is found that the longer axes of the bound dye molecules are almost parallel or perpendicular to a polypeptide chain, depending on whether ionization of the polypeptide is low or high.Recently we reported that various types of circular dichroism (CD) are induced on acridine orange bound to poly(S-carboxymethyl-L-cysteine) in solution. 1 These are observed at different pH and [P]/[D] (polymer residue/added dye) mixing ratios, and by polymers of different molecular weights. The observed CD is characteristic of the bonding species of the dye, dimeric dye or monomeric dye, as well as of the conformation of the polymer and can be classified into several types on the basis of the number and sign of the CD bands.Type I CD is induced on an aggregate of dimeric dyes bound to a polymer in the pconformation and has a pair of bands at 466 and 433 nm. A model for the binding mode has been presented and discussed, 2 ' 3 in which the dimeric dye molecules attach to ionized carboxyl groups and stack together to form linear arrays on both sides of an extended polypeptide chain. Types II and III CD have a pair of bands at 470 and 420 nm and additional bands at longer wavelength. These bands are opposite sign to each other for these two types. Types II' and III' CD have bands at 540 and 425 nm with opposite sign to each other. While Types II and 11 1 CD are exhibited by the solutions of random-coil polymers with low ionization, Types III and III' CD are characteristic of highly ionized random-coil polymers and of solutions of low [P]/[D] ratios.The acridine orange-poly(L-glutamic acid) mixture also induces Types III and III' CD at low [P]/[D] ratios and alkaline pH. 4 ' 5 The CD spectra similar to Types II and III were recently reported for an acridine orange-glycosaminoglycan mixture by Salter, et al.,6 whose designation accidentally coincided with our's except for Type I.Several theoretical investigations 7 -10 have attempted to evaluate the optical activity for the amide re-re* and n-re* transitions of polypeptide in random-coil conformation. However, these have relied on different approximations and methods and, consequently, have yielded inconsistent results. In the present work, we will apply a method of calculation to the optical 541

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“…In an attempt to calculate π°-π" and Πι-π~ rotational strengths for the random coil, Zubkov et al (1969Zubkov et al ( , 1971) applied the Monte-Carlo method of statistical analysis. This method can be summarized as follows: The (ψ, φ) steric map of the L-alanyl residue (Ramachandran et al, 1963) was subdivided into several regions, the greatly simplifying and tenuous assumption being made that the dipeptide conformation energy for any φ-ψ pair in a given region is uniformly the same.…”

Section: Random Coilmentioning

confidence: 99%