A DNA sequencing technique developed in 1976-1977 by Allan Maxam and Walter Gilbart to identify the sequence of nucleotide bases of a nucleic acid molecule by means of preferential, base-specific methylation (using dimethyl sulfate) and hydrazinolysis
This method involves DNA purification procedures and radioactive labelling at one end of the DNA to be sequenced. The molecule will next be treated with chemicals, each cleaving at specific bases (i.e. adenine, guanine, cytosine, or thymine). The result willl be a series of varying sizes of radioactive-labelled DNA fragments. These fragments will then be separatedthrough gel electrophoresis. The smallest fragments will travel farthest while the largest fragments will be nearest to the gel well. Thus, the sequence of nucleotide bases may be determined through the marks that the labelled fragments made on the gel.
It was once of the most utilized method of DNA sequencing. However, it became less favoured when more advanced sequencing methods came about owing to their less technical complexity, less use of health-hazard chemicals, and higher capability for large scale sequencing.