ddGTPare

ddGTPare is a laboratory reagent used in molecular biology, specifically in sequencing applications. It is a synthetic analog of deoxyguanosine triphosphate (dGTP), a naturally occurring building block of DNA. The key difference lies in the absence of a hydroxyl group at the 3' position of the sugar ring. This modification, known as a dideoxynucleotide, prevents the formation of a phosphodiester bond with the next incoming nucleotide.

In Sanger sequencing, ddGTP is incorporated into a growing DNA strand by DNA polymerase. Once a ddGTP is added, chain elongation terminates at that point because no further nucleotides can be attached. By using a mixture of ddGTP along with the other three standard deoxynucleotides (dATP, dCTP, and dTTP), and performing the reaction in separate tubes or using fluorescently labeled ddNTPs, fragments of varying lengths are generated, each ending with a specific ddGTP. These fragments can then be separated by size, and their sequence determined by identifying the terminal ddGTP at each position.

The use of ddGTP, along with its corresponding ddATP, ddCTP, and ddTTP, was foundational to the development of automated DNA sequencing technologies, enabling rapid and cost-effective determination of genetic material. While newer sequencing technologies exist, Sanger sequencing utilizing dideoxynucleotides remains a valuable tool for specific applications, such as verifying sequence data or analyzing short DNA fragments.