Maxam-Gilbert DNA sequencing

Maxam-Gilbert DNA sequencing relies on mcthylation of guanosine and adenosine nitrogens. Use SpartanView to examine electrostatic potential maps of 9-methyl-guanine and 9-methyladenine, and compare the electrostatic potentials at positions 7 on guanine and 3 on adenine. Which molecule is the better nucleophile, and why ... 

FIGURE 12.4 Maxam-Gilbert sequencing of DNA cleavage at purines uses dimethyl sulfate, followed by strand scission with piperidine. 

Maxam, A. M. Gilbert, W. Sequencing end-labeled DNA with base-specific chemical cleavages. Methods Enzymol. 1980, 65, 499-560. 

Figure 13.19 The Maxam and Gilbert method of DNA sequencing. The labelled DNA strand is divided into four aliquots. Each is treated to cleave the strand next to a different base resulting in a mixture of different length nucleotides. These nucleotides are separated by polyacrylamide gel electrophoresis and the DNA sequence read from the gel.

Determination of DNA Sequence Information. Almost all DNA sequence is determined by enzymatic methods (12) which exploit the properties of the enzyme DNA polymerase. Whereas a chemical method for DNA sequencing exists, its use has been supplanted for the most part in the initial determination of a sequence. Chemical or Maxam-Gilbert sequencing (13) is more often used for mapping functional sites on DNA fragments of known sequence. 

In 1970, Maxam and Gilbert and, in parallel, Sanger and Coulson, invented their method of DNA sequencing, of which, in principle, the latter is still in use today. 

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