DNA and oligonucleotides

The third type of experiment was performed to show that inhibition by the products is insufficient to account for the observed difference in rate. The substrate consisted of a 50 50 mixture (in terms of optical density) of native DNA and oligonucleotides. With this mixture the rate of hydrolysis decreased to about one-half of that for native DNA. This result agrees with the previously established (52) competitive-type inhibition by the products. It also shows that the inhibition by products accounts for changes in rate within one order of magnitude, whereas the decreasing affinity toward the newly formed substrates accounts for more than three orders of magnitude. With so pronounced a difference in susceptibility of substrate in the very early and in the very late phases of the reaction, the two phases must be considered independently. 

Enhanced electrochemical signals for DNA can be obtained by catalytic electrochemical oxidation using transition metal complexes/341 Studies by Thorp et al/35 01 showed that Ru(bpy)f+ (bpy=2,2 -bipyridine) is an efficient electrochemical catalyst that oxidizes only guanine bases in DNA and oligonucleotides. The reaction follows the catalytic pathway below ... 

The quality and reliability of microarray results largely depend on the quality and consistency of both the substrate and the reagents used to manufacture and process the arrays, but also on the considerable variation in the experimentalist s skills. A number of different substances have been tested as the solid support for nucleic acid immobilization [7,8], but glass slides are generally favored for DNA and oligonucleotide microarrays [9-11]. Optimal... 

DNA and oligonucleotides 458 1 1.6 Therapeutic monoclonal antibodies 460 Summary 460 References 460... 

DNA and oligonucleotides provide similar challenges - large hydrophilic molecules with no propensity for movement across cell walls and prone to degradation physically and chemically. 

Block-graft copolymers synthesized by covalent conjugation of Pluronic and branched PEI were used as materials for preparation of polyplexes. Such polyplexes usually contain three components (i) DNA (ii) Pluronic-PEI conjugate and (iii) free Pluronic (Fig. 7). The formulations were prepared with both plasmid DNA and oligonucleotides (ODN), resulting in stable polyplex dispersion with the particle size in the ranges of 100—200 nm. These polyplexes were used successfully for delivery of plasmid DNA and antisense ODN in vitro... 

Kawakami S, Higuchi Y, Hashida M (2008) Nonviral approaches for targeted delivery of plasmid DNA and oligonucleotide. J Pharm Sci 97 726-745... 

Conversely, DNA is functionally and structurally more stable than proteins it is easier to handle and interacts more favorably with surfaces. This provides a larger window for the choice of substrate, as well as for variations in attachment strategies. Many different schemes have been developed for immobilization of DNA and oligonucleotides on solid surfaces. Some thoroughly studied routes include covalent or electrostatic linking via functional silanized monolayers (see below), self-assembly of thiol-derivatized oligonucleotides on gold surfaces (Steel, 1999), or assembly of LB monolayers at the air-water interface (Okahata, 1996 Ijiro, 1996). 

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