Mismatches, in DNA

Nucleotide Chemistry The cells of many eukaryotic organisms have highly specialized systems that specifically repair G-T mismatches in DNA The mismatch is repaired to form a G=C (not A=T) base pair. This G-T mismatch repair mechanism occurs in addition to a more general system that repairs virtually all mismatches. Can you suggest why cells might require a specialized system to repair G-T mismatches ... 

Jackson BA, Barton JK. Recognition of base mismatches in DNA by 5,6-chrysenequinone diimine complexes of rhodium(III) A proposed mechanism for preferential binding in destabilized region of the double helix. Biochemistry 2000 39 6176-82. 

Figure 3 Monofunctional (top) and bifunctional (bottom) bulky metallointercalators that target single base mismatches in DNA. In the center is shown a view of the crystal structure of the complex inserted into the DNA from the minor groove at the mismatched DNA site, with ejection of the mismatched bases (14).

AUawi HT, SantaLucia J )r. Nearest neighbor thermodynamic parameters for internal G.A mismatches in DNA. Biochemistry 1998 37 2170-9. 

AUawi HT, SantaLucia J Jr. Nearest-neighbor thermodynamics of internal A.C mismatches in DNA sequence dependence and pH effects. Biochemistry 1998 37 9435-44. 

Yu CJ, Wan Y, Yowanto H et al (2001) Electronic detection of single-base mismatches in DNA with ferrocene-modified probes. J Am Chem Soc 123 11155-11161... 

For example, 2-aminopurine (AP) has been used to probe the dynamics of mismatches in DNA [340]. AP can be excited at 320 nm, where the normal DNA bases do not absorb (much), and emits at 380 nm (Fig. 4.36). Time-resolved anisotropy decays of AP across from all four natural DNA bases were performed (Fig. 4.37). AP can hydrogen-bond to T nearly as well as the natural A. The data were fitted to sums of two exponential terms the long time corresponded to overall tumbling and the short time to local motions within the DNA base stack. It was found that the internal correlation time corresponding to local motions, at 4°C,... 

Willner, L, Patolsky, F., Weizmann, Y., Willner, B. (2002). Amplified detection of single-base mismatches in DNA using micro gravimetric quartz-crystal-microbalance transduction. Talanta 56, 847-856. 

Several different DNA glycosylases are known to act on T G mismatches in DNA. The primary source of these mismatches is deamination of 5-methylcytosine (Duncan and Miller, 1980 Sved and Bird, 1990). 5-Methylcytosine is found in eukaryotes as an epigenetic modifier of chromatin structure and transcription, and in prokaryotes as the basis for self-protection from endogenous restriction enzymes. The human... 

Numerous electrochemical strategies have been developed for the detection of mismatches in DNA. These vary from the use of electroactive DNA intercalators to enzymatic signal amplihcation schemes, or redox-modified oligonucleotides. In the following sections, we will focus on the discussion of a range of electrochemical mismatch detection schemes. 

I Electrochemical Detection of Base pair Mismatches in DNA Films... 

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