Nucleic acid cleavage nuclease

In a given phosphodiester bond, hydrolytic enzymatic cleavage can occur at two locations, indicated by p and d in Figure 10.16. The former is proximal with respect to the 3 -OH group the latter is distal with respect to the 3 -OH. Enzymes that catalyze the hydrolysis of nucleic acids are nucleases (see Table 10.2). Exonucleases remove nucleotides (or nucleosides) from either the 5 or the 3 end of the polynucleotide. These are specific for either the p or the d bond. Thus, an exo-... 

Metal ions, especially Zn(II), play an important role in many enzyme-catalyzed reactions involving nucleic acids, such as DNA cleavage by zinc nuclease. Therefore, the binding of Zn(II) to a 19-mer double-stranded oligodeoxyribonucleotide was investigated to understand the role of zinc in DNA cleavage catalyzed by mung bean nuclease [107]. 

Endo- and exonucleases have been used successfully with nucleic acids and their analogs for organic synthetic purposes. For example, ATP was synthesized from AMP for use in cofactor recycling (Table 13-9, entry 1). The AMP was obtained from yeast RNA by cleavage with the nuclease Pi yielding a mixture of nucleoside monophosphates11011. In another report1731, nucleoside diphosphates were obtained by hydrolysis of RNA with nuclease Pi and a polynucleotide phosphorylase (the diphosphates are preferred because the diphosphates were more easily transformed to the nucleoside triphosphates than the monophosphates). 

Nucleases, such as ribonuclease (RNase) A or T, catalyze the hydrolysis of phospho-diester bonds in nucleic acids to produce oligonucleotides. Whereas the mammalian-type nuclease RNase A requires a pyrimidine base on the (3 )-side of the substrate, the microbial enzyme RNase T, requires a guanine [116]. Although the two families show hardly any sequence homology or structural relation, the cleavage mechanisms are believed to be similar [117-119]. 

The hydrolytic degradation of nucleic acids is catalyzed by nucleases, which are phosphodiesterases because they cleave the phosphodiesteric bonds hydrolytically (Linn et al., 1993). The cleavage can potentially occur on either side of the phosphorus atom, i.e. on the 3 -side (a) and the 5 -side (b) ... 

A. S. Boutorine, P.B. Arimondo, Se-quence-Specific Cleavage of Double-Stranded DNA, in M.A. Zenkova (ed.), Artificial Nucleases, Nucleic Acids and Molecular Biology, Vol. 13, Springer, Berlin (2004), p. 243. 

Nucleases a group of hydrolytic enzymes which cleave nucleic acids. Exonucleases attack the nucleic acid molecule at its terminus, whereas endonucleases are able to catalyse a hydrolytic cleavage within the polynucleotide chain. Deoxyribonucleases (DNAases) are specific for DNA, ribonucleases (RNAases) for RNA. All N. are Phosphodiesterases (see) they catalyse the hydrolysis of either the 3 or 5 bond of the 3, 5 -phosphodiester linkage. Ribonuclease (see) has been extensively studied. 

Dietary nucleic acids first pass through the stomach to the intestines, where they are hydrolyzed to their constituent nucleotides by a variety of different nucleases. Depbosphorylation by various nucleotidases next gives nucleosides, and cleavage by nucleosidases then gives the constituent bases, which are catabolized to produce intermediates that enter other metabolic processes or are excreted. 

Enzymatic polymerization is carried out by DNA and RNA polymerases, both of which carry out pyrophos-phorolysis, i.e., cleavage of a high energy pyrophosphate bond coupled to esterification of 5 phosphate linked to the 3 -OH of the previous residue. The reaction is reversible, although it strongly favors synthesis. Degradation of nucleic acids is not due to reversal of the reaction, but rather a hydrolytic reaction catalyzed by nucleases, namely, RNases and DNases, which generate nucleotides or deoxynucleotides, respectively. 

All the numerous cleavage possibilities listed probably are more significant for research on nucleic acids than for in vivo processes. In the cell the decisive role is played by the nucleases that break the high molecular nucleic acids into fragments of oligonucleotide size. These enzymes are able to degrade nucleic acids swiftly and to abolish their biologic activity. 

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