A-Oligonucleotides

Figure 27.7 A oligonucleotide modified at its 5 -phosphate with a diamine compound may be reacted with SPDP and subsequently reduced to create a free sulfhydryl.

When photobiotin is irradiated in the presence of DNA the reaction process non-selectively couples a biotin label to every 100—200 base residues. The result is a oligonucleotide probe detectable by the use of avidin or streptavidin conjugates. The uses of photobiotin for DNA or RNA modification are summarized in Chapter 8, Section 3.4. 

Another very sensitive MS technique is MALDI-TOF. Its high-resolution mass spectra allowed, for example, the identification of the 8-oxo-G lesion by its 416-Da mass shift in a oligonucleotide heptamer at picomol level (Bartolini and Johnston 2000). 

A Oligonucleotides Containing Modified Sugars. a-Anomeric oligoribonucleo-tldes a-rlls and a-rllu have been prepared on a solid-phase support from... 

Hilton, D. A., Love, S., and Barber, R. (1997) Demonstration of apoptotic cells in tissue sections by in situ hybridization using digoxigenin-labelled poly(A) oligonucleotide probes to detect thymidine-rich DNA sequences. J. Histochem. 

A linker containing a 2,4-bis(4-carboxyphenoxy)-6-methoxy-S-triazine amide group was introduced into a oligonucleotide using reagent 207. However, an aliphatic non-nucleotide linker was found to be more effective than an aromatic linker derived from 207, in stabilising oligonucleotides triplexes. ... 

Figure 8.7 Modification of oligonucleotides to increase stability, (a) Oligonucleotides (here shown as DNA) with a phosphodiester backbone (X = 0) are rapidly degraded by nucleases. Modification to create phosphorothioate analogs (X = S ) greatly increases half-life, (b) Peptide nucleic acids represent another DNA analog that can be used to bind with complementary sequences of oligonucleotides. Dashed lines represent hydrogen bonding which follows Watson-Crick base pairs.

Enzyme Nanolithography, Fig. 4 (a) Oligonucleotide enzyme, which digests the oligonucleotide layer (Scheme SAM. (b) Deposition of DNase I with DPN. (c) Inactive 1 from Ref [7])... 

The P-D configuration corresponds to natural DNA. The first a-oligonucleotide was synthesised in 1986 and a number of others corresponding to the other isomers in (10.91) have since been prepared [60]. 

In addition to single-stranded a-oligonucleotides, stable a-P double-stranded varieties have been made (Figure 10.60). It is not yet known whether short lengths of a-chains exist in, or can be inserted into, the long lengths of P-chains which constitute natural DNA or RNA. Interest in such unnatural forms of DNA stems from expected differences in their interaction with enzymes and other biochemical behaviour compared to that of natural P-DNA. 

SMART II A oligonucleotide (lOmM) 5 -dAAGCAGTGGTATCAACGCAGAG-TACGC-rGGG-3. ... 

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