Deoxyribonucleic acid, preparation

The Helical Nature of Nucleic Acids. The double helix of nucleic acids has a diameter of 20 A. Dimensions such as these can be made visible in modern electron microscopes. In the photograph of a deoxyribonucleic acid preparation of bacteriophages (Fig. 28), even the twisted structure of the DNA can be distinguished. The entire, multiply looped thread is 500,000 A (= 50 /u) long, which corresponds to a molecular weight of 130 million. 

Mosharrafa, E. T., Schachtele, C. F., Reilly, B. E., Anderson, D. L. Complementary strands of bacteriophage 029 deoxyribonucleic acid Preparative separation and transcription studies. J. Virol. 6, 855-864 (1970). 

Deoxyribonucleic acids readily undergo hydrolysis whereby purine bases are removed to give a derived polynucleotide originally named thymic acid, but now often called apurinic acid. Hydrolysis may be carried out with dilute mineral acid, but recently apurinic acids have been prepared by fission at room temperature with an acidic, ion-exchange resin.236 Under carefully controlled conditions, removal of the purines can be performed quantitatively without destroying the polynucleotide nature of the material and without altering the inter-pyrimidine ratios of the original material.23 ... 

Values found for the molecular weight of deoxyribonucleic acids also vary considerably, but probably lie between 1.0 X 106 and 4.4 X 106. Various difficulties encountered in making such measurements have been discussed by Jordan,244 and it is probable that more reliable information will be obtained only when the behavior of polyelectrolytes in general is better understood. Certain of the techniques used are useful in detecting differences between different nucleic-acid preparations, but the discrepancies between the values given by different methods of measurement appear to vary with the degree of polymerization.246... 

Condensation polymers consisting of the Michael addition product of ami-noethylpiperazine with 1,4-butanediacrylate, (I), as illustrated in Eq. (2) were prepared by Liu et al. (2) and used as vectors for delivery of DNA (deoxyribonucleic acid) to a cell. 

There is an ongoing requirement in cell and molecular biology for the preparation of antibodies to use as probes for specific proteins. Two main strategies exist to raise appropriate antibodies. A complimentary deoxyribonucleic acid (cDNA), or gene sequence encoding the protein of interest can be expressed in a heterologous species,... 

Fig. 4.—Hydrolysis48 of 6.3 X 10-4 M Phenolphthalein 0-D-Glucosiduronic acid at Various pH Values, in 0.05 N Acetate Buffer, by a Highly Purified 0-Glucuronidase Preparation from Female-rat Preputial Gland (Section IV), Alone (X), and in Presence of 0.03 % of Deoxyribonucleic Acid (O), or of 0.01% of Albumin ( ).

Walsh (2003) defined biopharmaceuticals as therapeutic protein or nucleic acid preparations made by techniques involving recombinant deoxyribonucleic acid (DNA) technology. Therapeutic proteins include blood clotting factors and plasminogen activators, hemopoietic factors, hormones, interferons and interleukins, and monoclonal antibodies (LeVine, 2006). Over time, the term biopharmaceutical has broadened, and, in addition to proteins and nucleic acids, now includes bacteriophages, viral and bacterial vaccines, vectors for gene therapy, and cells for cell therapy (Primrose and Twyman, 2004). Attention here focuses on proteins, since the majority of approved biopharmaceuticals are proteins. 

Purines are some of the most ubiquitous heterocydes. The quantity of naturally occurring purines produced on the earth is enormous, as 50% of ribo- and 2 -deoxyribonucleic acid (RNA, DNA) bases are purines. Purine is a colorless, crystalline weak base which was first prepared by E. Fischer by zinc dust reduction of 2,6-diiodopurine, which had been obtained from 2,6,8-trichloropurine by reaction with hydrogen iodide and phosphonium iodide. 

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