Mie scattering contributions to the optical density and circular dichroism of T2 bacteriophage

Holzwarth, G.; Gordon, David G.; McGinness, James E.; Dorman, Burton P.; Maestre, Marcos F.

doi:10.1021/bi00698a020

Cited by 68 publications

(29 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To the suggestion that the CD spectrum of $-DNA represents a mere artifact caused either by scattering or some other effect of aggregation, however, we can reply that although some scatter-distortion is present, by comparison with other systems [22] it comprises no more than a small fraction of the total CD changes observed. We find that CD spectra of $-DNA samples taken at 27°C both in a standard cuvette and in a fluorscat cell, which largely corrects for scattering artifacts [ lo], show only minor differences, primarily a diminution of the long-wavelength 'tail' above 300 nm and a slight enhancement and l-2 nm blue shift of the 263-264 nm band.…”

Section: Resultsmentioning

confidence: 61%

“…We cannot at present ascribe any concrete biological significance to $-DNA as neither whole bacteriophage [22], nor chromatin [28], nor intact rat thymus nuclei [29] exhibit CD spectra in the DNA region corresponding exactly to that of $-DNA. Nevertheless, the $-form offers a reversibly attainable state of great compactness available to bihelical (and trihelical [ 111) nucleic acids and it would seem unwise to dismiss it prematurely as irrelevant to their in vivo condition.…”

Section: Resultsmentioning

confidence: 99%

“…At the very least one might ask whether its CD spectrum should not be included in the basis set (along with A-, B-, and C-form spectra) when attempting to interpret observed CD spectra of biological materials as linear combinations of standard spectra [30]. (The CD difference spectrum between intact and disrupted T2 bacteriophage [22] which strikingly resembles the G-DNA spectrum provides a case in point.) Finally we note that since the $ transition can be effected quite easily in vitro the absence of a significant amount of @DNA in vivo may imply that some factor(s) actively inhibits this transition.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

The thermal transition of ‘PSI’ DNA monitored by circular dichroism

Cheng

Mohr

1974

FEBS Letters

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The thermal transition of ‘PSI’ DNA monitored by circular dichroism

Cheng

Mohr

1974

FEBS Letters

View full text Add to dashboard Cite

“…These methods were limited originally to homogeneous solutions of macromolecules. More recently, they also have been applied to increasingly complex systems such as viruses (1,2), erythrocytes (3,4), nucleohistones (5,6), DNA-polylysine complexes (7,8), DNA aggregates (9), chloroplasts (10), etc. (11).…”

mentioning

confidence: 99%

“…Many qualitative explanations for the anomalies were proposed, including differential scattering of left and right circularly polarized light, light absorption so intense that the interior of the aggregate could no longer contribute to absorption (Duysens flattening of absorption peaks), and liquid crystal behavior (2)(3)(4)(12)(13)(14)(15). Quantitative explanations based on phenomenological equations also were presented.…”

mentioning

confidence: 99%

Circular differential scattering can be an important part of the circular dichroism of macromolecules.

Bustamante¹,

Tinoco²,

Maestre³

1983

Proc. Natl. Acad. Sci. U.S.A.

164

149

View full text Add to dashboard Cite

Differential scattering of incident left and right circularly polarized light can be an important contribution to the circular dichroism of macromolecules. In principle both differential absorption and differential scattering of circularly polarized light contribute to circular dichroism, but differential scattering is increasingly important for particles whose dimensions are greater than 1/20th the wavelength of light. The scattering contribution is probably not important for unaggregated proteins and nucleic acids in solution. It can be very important for viruses, membranes, and other protein-nucleic acid complexes. Outside the absorption bands of the scattering, chiral particle, only differential scattering contributes to the circular dichroism. The sign and magnitude of the differential scattering is quantitatively related to the relative orientations and the distances between the scattering units of the particle. The interpretation of the circular differential scattering depends on a simple, classical method. Thus, in understanding a measured circular dichroism, it often will be easier to relate the differential scattering to the structure of a particle (such as a virus) than it is to relate the differential absorption to the structure. CD and optical rotatory dispersion (ORD) studies have been helpful in providing useful knowledge about the structure of biological macromolecules. These methods were limited originally to homogeneous solutions of macromolecules. More recently, they also have been applied to increasingly complex systems such as viruses (1, 2), erythrocytes (3, 4), nucleohistones (5, 6), DNA-polylysine complexes (7,8), DNA aggregates (9), chloroplasts (10), etc. (11). A remarkable common feature of many of these systems was the presence of anomalies in their CD and optical rotatory dispersion spectra. The CD spectra presented: (i) apparent differential absorption of circularly polarized light outside of the absorption bands (the CD signal at long wavelengths was slowly varying but non-zero; this longwavelength "tail" could be positive or negative); (ii) signals sensitive to the distance of the photomultiplier from the sample; and (iii) CD values 1 or 2 orders of magnitude larger than normal. Fig. 1 Recently, a new quantitative understanding of differential scattering of circularly polarized light has been obtained. We were able to relate the difference in scattering efficiency for incident left and right circularly polarized light to the detailed structure of the scattering particle (20-24). We have measured the angular dependence of this circular intensity differential scattering for a helix of known structure and obtained good agreement with theory (25). Thus, we now can explain the "anomalous" behavior of chiral macromolecules and aggregates. We find that the scattering "artifacts" can provide valuable information about the configuration (left-or right-handed) of the component particles.Here we will show how the differential scattering of left and right circularly polarized light ...

show abstract

Dilute Random Distribution of Small Chiral Ellipsoids in a Chiral Fluid: Optical Properties

Lakhtakia¹

1990

Ber Bunsenges Phys Chem

View full text Add to dashboard Cite

An integral equation method has been used to derive the polarizabilities of a small chiral ellipsoid immersed in a chiral fluid. These polarizabilities are then used to obtain the effective electromagnetic/optical properties of a dilute random suspension consisting of randomly‐oriented, ellipsoidal, chiral particles in a chiral fluid. The optical rotation and the circular dichroism of the suspension are obtained.

show abstract

Mie scattering contributions to the optical density and circular dichroism of T2 bacteriophage

Cited by 68 publications

References 35 publications

The thermal transition of ‘PSI’ DNA monitored by circular dichroism

The thermal transition of ‘PSI’ DNA monitored by circular dichroism

Circular differential scattering can be an important part of the circular dichroism of macromolecules.

Dilute Random Distribution of Small Chiral Ellipsoids in a Chiral Fluid: Optical Properties

Contact Info

Product

Resources

About