Deoxyribonucleic acid enzymic degradation

Deoxyribonuclease (DNAase), an enzyme that degrades deoxyribonucleic acid, has been used in patients with chronic bronchitis, and found to produce favorable responses presumably by degrading the DNA, contributed by cell nuclei, to inflammatory mucus (213). Lysozyme [9001 -63-2] hydrolyzes the mucopeptides of bacterial cell walls. Accordingly, it has been used as an antibacterial agent, usually in combination with standard antibiotics. Topical apphcations are also useful in the debridement of serious bums, cellulitis, and dermal ulceration. 

The carbohydrate component of ribonucleic acid and, therefore, of the corresponding purine nucleosides was identified as a pentose by Hammar-sten and, later, as D-ribose by degradation and then by synthesis. Because of the instability of 2-deoxy-D-erythro-peutose ( 2-deoxy-D-ribose ), its isolation from deoxyribonucleic acid was much more difficult. Levene and coworkers finally obtained the crystalline sugar from deoxyguanosine by brief treatment with dilute mineral acid. They established its identity by comparison with synthetic 2-deoxy-D-threo-pentose and 2-deoxy-L-er /[Pg.303]

Deoxyribonucleic acids are much more alkali-resistent than ribonucleic acids and require other enzyme systems for hydrolitic degradation. Hydrolysis of deoxyribonucleic acids with mineral acids splits off purine bases, yielding thymic acid and oligonucleotides can be prepared through the action of pancreatic enzymes. 

Deoxyribonucleic Acid, Since only carbons 3 and 5 of the 2-deoxyribose are available for esterification in DNA, the linkages are all most probably of the 3, 5 -type. Purified phosphodiesterase quantitatively liberates 5 -mononucleotides from thymus DNA 100), On the other hand, no method has as yet been developed for degradation of these nucleic acid to 3 -deoxy-mononucleotides, although the pyrimidine 3, 5 -diphosphates have been isolated from acid hydrolyzates of DNA. Crystalline pancreatic deoxyribonuclease rapidly degrades DNA to very low molecular weight polynucleotides, but identification of many of these products reveals no certain route for the action of the enzyme 168),... 

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