Desoxyribonucleic acid molecular weight

Fig. 5.6. Ratio of Maxwell-constant to intrinsic viscosity as a function of molecular weight for fractions of desoxyribonucleic acid in 0.15 molar aqueous sodium chloride solution at 21° C according to Frisman, Vorob ev and Shchagina (162)...

Biopolymers are either synthesized by template-dependent or template-independent enzymatic processes. For the synthesis of nucleic acids and proteins a template is required, whereas all other polymers are synthesized by template-independent processes. The templates for nucleic acids are desoxyribonucleic acids or ribonucleic acids depending on the type of nucleic acid synthesized. For proteins, the template is messenger ribonucleic acid (mRNA). This has different impacts on the structure and on the molecular weights (MWs) of the polymers. Although both nucleic acids and proteins are copolymers with each type consisting of 4 or 22 different constituents, respectively, the distribution of the constituents is absolutely defined by the matrix and is not random. Furthermore, each representative of the two polymers has a defined MW. Polymers synthesized in template-dependent processes are monodisperse. All this is different in polymers synthesized by template-independent processes first of all, these polymers are polydisperse secondly, if these polymers are copolymers, the distribution of the constituents is more or less fully random. 

The desoxyribonucleic are more stable than the ribonucleic acids and, consequently, a greater number of results have been obtained in determinations of their molecular weight. They are very elongated, threadlike molecules, whose molecular weight is in the region of six million. 

Nucleic acids are polymerized nucleotides which occur associated with basic proteins as nucleoproteins. Nucleotides, as they are isolated from hydrolyzates of nucleic acids, are phosphoric esters of nucleosides. Nucleosides are /3-D-ribofuranosides or jS-D-2-desoxyribofuranosides of purines or pyrimidines linked at Ng or N3, respectively. Ribonucleic acids (RNA) occur universally and contain, as nitrogenous bases, adenine, guanine, cytosine, and uracil. Desoxyribonucleic acids (DNA) occur mainly in cell nuclei and animal viruses. DNA contain the same nitrogenous bases as RNA with the important exception that uracil is replaced by thymine. Samples of RNA or DNA from various sources differ in molecular weight and in the proportions of the four nitrogenous bases they contain. 

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See also in sourсe #XX -- [ ]

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