MaxamGilbert

The Maxam-Gilbert sequencing method is a technique used to determine the nucleotide sequence of DNA. Developed by Allan Maxam and Walter Gilbert in 1977, it was one of the first rapid DNA sequencing methods available, preceding the Sanger sequencing method by only a few months.

The Maxam-Gilbert method relies on the chemical cleavage of DNA at specific bases. The process involves selectively modifying the DNA bases and then cleaving the DNA backbone at those modified sites. This is typically achieved using a series of chemical reactions. For example, one reaction might cleave DNA primarily at guanine residues, another at adenine and guanine, another at cytosine and thymine, and a final one only at cytosine.

After the chemical treatments, the resulting DNA fragments are separated by size using gel electrophoresis. The separated fragments are then visualized, often by labeling the original DNA with a radioactive isotope. The pattern of bands on the gel reveals the sequence of the DNA. A distinct band at a certain position indicates a fragment of that specific length, corresponding to a particular nucleotide at that position in the original sequence.

While historically significant, the Maxam-Gilbert method has largely been superseded by automated Sanger sequencing and next-generation sequencing technologies due to its complexity, the use of toxic chemicals, and its lower throughput compared to modern methods. However, its development was a crucial step in the advancement of molecular biology and genetics.