Matsushita of Japan, commonly known as Panasonic, has developed a technique to electronically identify single nucleotide polymorphisms in a DNA solution without direct contact between the molecules and electrodes. Knowledge of one’s DNA variance (in the form of nucleotide polymorphisms) can point to differences in individual response to specific pharmaceuticals, as well as risks of having a certain disease.
Details of the technology:
To identify SNPs by using a replication reaction for the target DNA an artificially synthesized piece of single-strand short DNA consisting of approximately 20 bases is prepared. The base sequence of this artificial DNA is designed to correspond to that of the target DNA. If the SNP of the target DNA is complementary to the SNP-corresponding nucleotide of the artificial DNA, the replication reaction of the artificial DNA occurs; however, the replication reaction does not occur if the SNP is not complementary. A SNP can be identified accurately by using this reaction.
Conventional electrical SNP identification requires specialized and expensive electrodes, on which artificial testing DNA is attached. However, there are still problems in controlling the quantity to be secured and the variation in the result. Another approach is an optical identification method using fluorescent dyes without attaching DNA to an electrode, but this requires large and expensive equipment along with an optics system.
Panasonic’s improved new method can identify SNPs electrically with artificial DNA dissolved in a solution instead of being attached to the electrode.
Panasonic discovered that when artificial DNA is prepared with a base sequence that is non-complementary to the second and third bases from the SNP of the target DNA, a replication reaction from the artificial DNA occurs if the SNP is complementary to the SNP-corresponding nucleotide; however, no replication reaction occurs if it is not complementary.
During DNA replication, a single molecule of a phosphate compound called pyrophoric acid is released as a reaction byproduct every time a base is replicated. Panasonic has developed a new enzyme reaction system for converting the quantity of pyrophoric acid into an electrical current. By using three types of enzymes, the quantity of pyrophoric acid is converted to an equivalent quantity of potassium ferrocyanide, an electron mediator, making measurement of the oxidation current possible, a world-first achievement.