Nuclease location

Restriction Endo nuclease Location on Map (g-k ) Recognition Sequence Content — Recognition Sequence + ... 

Analysis of the chromatin organization of integrated HIV-1 identified a single major nuclease-hypersensitive site in the 8 kb region located between the two LTRs (Verdin, 1991 Van Lint et al, 1994). This hypersensitive site, centered around nt... 

Most pre-mRNA transcripts are cleaved post-transcriptionally near the 3 end between a polyadenylation signal (5 -AAUAAA-3 ) and 5 -YA-3 (where Y = a pyrimidine). A GU-rich sequence may also be located further downstream. Specific proteins bind to these sequence elements to form a complex. One of the bound proteins, poly(A) polymerase, then adds a poly(A) tail of up to 250 A residues to the new 3 end of the RNA molecule and poly(A) binding protein molecules bind to this. The poly(A) tail protects the 3 end of the final mRNA against nuclease degradation and also increases translational efficiency of the mRNA. Some pre-mRNAs (e.g. histone pre-mRNAs) are cleaved near the 3 end but no poly(A) tail is added. 

The distortions induced in the DNA double helix by the interstrand cross-links have been characterized by several techniques. As judged by chemical probes (diethyl pyrocarbonate, hydroxylamine, osmium tetroxide), antibodies to cisplatin-modified poly(dG-dC)-poly(dG-dC), natural (DNase I) and artificial (1,10-phenanthroline-copper complex) nucleases, the cytosine residues are accessible to the solvent, and the distortions are located at the level of the adduct [48-50]. From the electrophoretic mobility of the multimers of double-stranded oligonucleotides containing a single interstrand cross-link [50] it is deduced that the DNA double helix is unwound (79°) and its axis is bent (45°). 

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-... 

Is there any specificity with respect to the location of the bond to be cleaved by a nuclease within the polynucleotide chain ... 

Besides proteases and nucleases some lipoxygenases [140,141] are also located in the cytosol of cells [142]. Lipoxygenases react with polyunsaturated fatty acids (PUFAs), containing one or several double allylically activated CHa groups (-CH=CH-CH2-CH=CH-) [140,141]. PUFAs are mainly localized at position 2 of a phospholipide [143]. This is exactly the site where phospholipases Aa - liberated by cell injury -attack phospholipides. 

Upon administration to the body, plasmid DNA or its complex with any vector, interacts with cells, proteins, and extracellular matrix. The summation of these interactions will determine the in vivo fate of plasmid DNA and its complex, which, in turn, determines the location and extent of gene transfer. From a pharmaceutical and biopharmaceutical point of view, plasmid DNA is a huge macromolecule with a strong negative charge, and it is susceptible to attack by nucleases. 

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