Deoxyribonuclease inactivation

Okada, S. and Gehrmann, G. (1957). Inactivation of deoxyribonuclease I by X-rays. Biochim. Biophys. Acta 25, 179-182. 

The TNF-a-induced DNA fragmentation may have been caused by caspase-activated deoxyribonuclease (CAD) in PC-12 cells. In non-apoptotic cells, CAD is present as an inactive complex with the inhibitor jOvd p3,24]. During apoptosis, caspase-3 inactivates ICAD, leaving CAD free to function as a nuclease [25]. Therefore, we used die fluorogenic substrate, Ac-DEVD-MCA, to determine whether the caspase-3 in PC-12 cells was activated by treatment with TNF-a and/or crocin. As shown in... 

However, in 1944, Avery and associates showed that purified DNA extracted from pneumococci could carry out transformation.8 12 The transforming principal appeared to contain little protein. It was not inactivated by proteolytic enzymes but was inactivated by deoxyribonuclease. Avery was 67 at the time of this discovery, refuting the popular contention that all important scientific discoveries are made by young people. 

T,-H. Liao. Reversible inactivation of pancreatic deoxyribonuclease A by sodium dodecyl sulfaic. Removal of the CQOH emninal residues from the denatured protein by csiboxypeptldase A. J. BioL Chem. 250 3831-3836 (1975). 

In the body, enzymes are compartmentalized and function under highly restricted conditions. Some enzymes (e.g., proteinases) are not substrate-specific. When present in active form in an inappropriate part of the body, they act indiscriminately and cause considerable damage to the tissue. Inhibitors inactivate these enzymes at sites where their action is not desired. Proteinase inhibitors, which are themselves proteins, are widely distributed in intracellular and extracellular fluids. Protein inhibitors of enzymes other than proteinases are relatively rare. Such inhibitors are available for a-amylases, deoxyribonuclease I, phospholipase A, and protein kinases. 

Bernardi G. and Bach M.L. (1968). Studies on acid deoxyribonuclease. VII. Inactivation of Haemophilus influenzae transforming DNA by spleen acid deoxyribonuclease. J. Mol. Biol. 37 87-98. 

Incubation of the inhibitory fraction with different enzymes has shown no inactivation by pancreatic ribonuclease, ribonuclease Ti from Aspergillus oryzae or deoxyribonuclease. The inhibitory activity is also not diminished by the proteolytic enzymes typsin and papain. However, incubation with preincubated pronase, a proteolytic enzyme from Asper-... 

Some enzymes are rendered inactive by specific or unspecific inhibitors, as in the case of ribonuclease and deoxyribonuclease. Other enzymes have latent activity because their active center is in some way inactivated by some polypeptidic chain in the molecule. Once the inhibiting chain has been removed by the action of proteolytic enzymes, the enzyme becomes fully active, as is the case for example, for thrombin and chymotrypsin. Finally, the activity of some enzymes is kept latent because of the absence of a cofactor e.g., phenylpyruvic hydroxylase in the developing liver). 

The different procedures for isolating nucleic acids yield products which vary considerably in composition and properties. One reason for this is the presence of nucleolytic enzymes in most plant and animal tissues. Work is always carried out at as low a temperature as possible to retard this enzyme activity and sodium citrate is used in an attempt to inhibit the action of deoxyribonucleases ribonucleases are inactivated with guanidine hydrochloride or dodecylsulphate. 

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