Conformation of Viral Nucleic Acids in Situ

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Publisher Summary The problems that are discussed in this chapter are confined to viruses, and to be more exact, to the question of similarities and differences between the structure and properties of usual forms of nucleic acids in solution and that of nucleic acids inside viral particles. Such differences should exist, as the viral particle is a rather peculiar and highly specialized object designed for storage and transport of the genetic substance of viruses. The properties of nucleic acids in situ ought to be affected by the environment, which they have in viruses, by the special functions that they have to perform, by their close partnership with protein, and by a number of other intraviral factors of which very little is known. The bulk of the information dealt with in this chapter is obtained by the means of X-ray diffraction and electron microscopy, various combinations of optical methods, and chemical and physical modifications combined with some way of recording corresponding results. There are a number of theoretical and practical difficulties to be overcome, which are discussed in detail in this chapter. Determination of true absorption, values of objects that scatter light in the region where they absorb, is always a matter of difficulty when conformation of intraviral nucleic acid is studied by means of absorption, anisotropic absorption, or optical rotatory dispersion (ORD). The use of the extrapolation method is often objected to form a theoretical point of view. The more specific problem of obscurity of UV dichroism data and some others are considered in this chapter.