Nucleolytic Enzymes

It should, however, be noted that in none of the foregoing investigations were attempts made to carry out macroelectrolysis with a view to identification of products. Even more surprising is the fact that there are no reported trials of the use of various commercially available nucleolytic enzymes to hydrolyze reduced oligonucleotide products, which might have rendered possible at least partial, if not complete, identification of the electrochemically modified monomeric units by simple paper or thin-layer chromatography in conjunction with UV spectroscopy. 

Oligonucleotides with incorporated xylo-nucleosides attract a lot of interest because they are more resistant towards nucleolytic enzymes compared to natural oligodeoxyribonucleotides [64, 65]. The corresponding oligodeoxyxyZo-nu-cleotides with incorporated phosphorothioate linkages should be even more... 

Telomere length is maintained by telomerase, an enzyme composed of one polypeptide subunit and one RNA subunit. The catalytic subunit of telomerase bears homology to retroviral reverse transcriptases, consistent with its role in catalyzing synthesis of DNA on an RNA template. The 3 end of a telomeric G-rich overhang is the primer for addition of new telomeric sequence, which is templated by the complementary sequence in the telomerase RNA subunit. In vitro, G-rich telomeric sequences readily form G-quadruplexes with distinctive structural features determined by telomere sequence and strand orientation. G4 DNA formation could in principle promote telomere telomere interaction [Figure 4(A)] protect the 3 end from extension or nucleolytic attack [Figure 4(B)] or stabilize t-loops [Figure 4(C)]. 

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. 

The probability is very strong that complete depolymerization of nucleic acids to the stage of nucleotides requires the intervention of more than one enzyme. Studies on the distribution of nucleolytic activity have shown it to be common among diverse cells. 

Diastereoisomeric purity of the title oUgonucleotides has been checked by means of two nucleolytic enzymes, snake venom phosphodiesterase (SVPDE) and nuclease PI of known diastereoselectivity toward dinucleoside phosphorothioates. Although SVPDE hydrolyzes only... 

Bovine pancreatic deoxyribonuclease (DNase I) is an endonuclease that cleaves both ssDNA and dsDNA to produce primarily 5 -P dinucleotides and 5 -P oligonucleotides (Fig. 3.1). DNase I degrades dsDNA in a sequence-nonspecific manner. The enzyme requires divalent cations (both Ca and Mg or Mn ) as cofactors for full double-strand cutting activity. In the presence of Mg alone as a cofactor, DNase I exhibits nicking activity and the single-strand nucleolytic activity is more discriminatory. 

Based on the observations that a variety of altered duplex structures can elicit nucleolytic cleavages by Bal31, it has been postulated that Bal31 enzymes act on structures bearing relative thermodynamic instability (3). The canonical exonuclease activity against linear dsDNA may well be regarded as a manifestation of the activity at the thermodynamically unstable termini. 

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