Tomas D Brook: Discovered A Bacteria in Yellowstone National Park In The USA.
He separated the bacteria from the hot spring of water and named it as Thermus aquatics. The bacteria can survive at higher temperature therefore the name Thermus was given and as it was found in hot water name aquatics had given to it. It is called as Thermous aquatics, A hot water bacteria. Then, in the year 1976, Chien et al.
Isolated polymerase from Thermus aquatics and named it as Taq DNA polymerase. Presently, this is an enzyme which can solve the problem for PCR. The reason behind its use in PCR is the stability of the enzyme at a higher temperature.
Advantages of Taq DNA Polymerase:
- Obviously, Thermostable: The enzyme is thermostable polymerase hence it can even work at a higher temperature.
- Efficiency: It is highly efficient. As it is reached at its optimum temperature, the thermostable polymerase becomes fully functional and adds nucleotides to the growing DNA strand.
- Hight amplification capacity: It can insert 150 nucleotides per second during amplification. The half-life of thermostable polymerase is higher than anyone commercially available polymerase. Taq has a half-life of more than 2 hours at temperate of 92°c.
Disadvantages of Taq DNA Polymerase:
- Low Specificity: The specificity of Taq DNA polymerase activity is lower as compared with normal polymerase, it can add even mismatched nucleotides. Because it is a temperature-dependent, slight fluctuation in temperature causes an adverse effect in Taq activity.
- Low fidelity: Taq does not have 3' to 5' exonuclease proofreading activity so it is unable to correct the mismatched nucleotide.
- Unidirectional activity: Again, it has unidirectional activity from 5' to 3' therefore it cannot go back for base excision repair.
- Bivalent cation requirement: The enzyme required cofactors for working properly. The Taq DNA polymerase always needs an Mg2+ ion as a cofactor.