High nucleic acids

High nucleic acid/polymer affinity does not necessarily directly correlate with high efficiency. Apparently, an optimum has to be reached. Also, the big difference in size of different medical nucleic acids (pDNA has several thousand negative... 

The amount of nucleic acid in tissues varies from 0.1% in yeast and 0.5-1% in muscle and in bacteria to 15-40% in thymus gland and sperm cells. In these latter materials of high nucleic acid content it is clear that multiplication of % N by 6.25 is not a valid measure of protein content. For diploid cells of the body the DNA content per cell is nearly constant. 

This effect was observable only because of the high nucleic acid content of the phages which permits observation by the ultraviolet light absorption method at concentrations below 0.25 mg. per ml. 

Protamines. Strongly basic, low mol. wt. proteins which contain high levels of arginine, but no sulphur-containing amino-acids. They are soluble proteins, associated with nucleic acids and are obtained in large quantity from fish spermatozoa. 

Plasmid DNAs. Plasmids are nucleic acid molecules capable of intracellular extrachromosomal repHcation. Usually plasmids are circular DNA species, but linear and RNA plasmids are known. In nature, plasmids can assume a variety of lifestyles. Plasmids can recombine into the host chromosome, be packaged into vims particles, and repHcate at high or low copy number relative to the host chromosome. Additionally, their information can affect the host phenotype. Whereas no single plasmid is usually capable of all these behaviors, the properties of various plasmids have been used to constmct vectors for a variety of purposes. 

Nucleic acid (deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)) probes utilize labeled, ie, radioactive, enzymatic, or fluorescent, fragments of DNA or RNA (the probe) to detect complimentary DNA or RNA sequences in a sample. Because the probe is tailored for one specific nucleic acid, these assays are highly specific and very sensitive (45). 

As the result of high specificity and sensitivity, nucleic acid probes are in direct competition with immunoassay for the analytes of some types of clinical analytes, such as infectious disease testing. Assays are being developed, however, that combine both probe and immunoassay technology. In such hybrid probe—immunoassays, the immunoassay portion detects and amplifies the specific binding of the probe to a nucleic acid. Either the probe per se or probe labeled with a specific compound is detected by the antibody, which in turn is labeled with an enzyme or fluorophore that serves as the basis for detection. 

Zinc. The 2—3 g of zinc in the human body are widely distributed in every tissue and tissue duid (90—92). About 90 wt % is in muscle and bone unusually high concentrations are in the choroid of the eye and in the prostate gland (93). Almost all of the zinc in the blood is associated with carbonic anhydrase in the erythrocytes (94). Zinc is concentrated in nucleic acids (90), and found in the nuclear, mitochondrial, and supernatant fractions of all cells. 

En me Mechanism. Staphylococcal nuclease (SNase) accelerates the hydrolysis of phosphodiester bonds in nucleic acids (qv) some 10 -fold over the uncatalyzed rate (r93 and references therein). Mutagenesis studies in which Glu43 has been replaced by Asp or Gin have shown Glu to be important for high catalytic activity. The enzyme mechanism is thought to involve base catalysis in which Glu43 acts as a general base and activates a water molecule that attacks the phosphodiester backbone of DNA. To study this mechanistic possibiUty further, Glu was replaced by two unnatural amino acids. 

Fohc acid is a precursor of several important enzyme cofactors required for the synthesis of nucleic acids (qv) and the metaboHsm of certain amino acids. Fohc acid deficiency results in an inabiUty to produce deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and certain proteins (qv). Megaloblastic anemia is a common symptom of folate deficiency owing to rapid red blood cell turnover and the high metaboHc requirement of hematopoietic tissue. One of the clinical signs of acute folate deficiency includes a red and painhil tongue. Vitamin B 2 folate share a common metaboHc pathway, the methionine synthase reaction. Therefore a differential diagnosis is required to measure foHc acid deficiency because both foHc acid and vitamin B 2 deficiency cause... 

Extraction of proteia requires breaking the cell wall to release the cytoplasmic contents. This can be achieved by high speed ball or coUoid mills or by high pressure (50—60 Mpa) extmsion. Proteia is extracted by alkaline treatment followed by precipitation after enzymatic hydrolysis of nucleic acids. Although the proteia can be spun iato fibers or texturized, such products are more expensive than those derived from soybean and there is no market for them. 

High matrix rigidity is offered by porous sihca, which can be deriva-tized to enhance its compatibility with proteins, but it is unstable at alkaline pH. Hydroxyapatite particles have high selectivity for a wide range of proteins and nucleic acids. 

Commercial use of cell and tissue culture continues to expand. Improvement of organisms through recombinant nucleic acid techniques has become commonplace. Formerly, a few laboratories were well ahead of most others, but now the methods have been perfected for routine use. Another technique that is widely practiced is culturing of cells that excrete high concentrations of just one antibody protein. The specificity of antibodies and antigens is exploited in medical testing procedures using these pure monoclonal antibodies. 

---