Taq dna polymerase - enzyme used in PCR amplification technology

PCR amplification enzyme- taq DNA polymerase enzyme

1. Taq DNA polymerase NEERAJA - A

2. What is taq dna polymerase? Taq  polymerase  is a thermostable  DNA polymerase  named after the  thermophilic  bacterium  Thermus aquaticus  from which it was originally isolated. It is frequently used in the  polymerase chain reaction  (PCR), a method for greatly amplifying the quantity of short segments of  DNA .

3. Taq polymerase T. aquaticus  is a  bacterium  that lives in  hot springs  and  hydrothermal vents , and  Taq  polymerase was identified as an  enzyme  able to withstand the protein-denaturing conditions (high temperature) required during PCR. Therefore, it replaced the DNA polymerase from  E. coli  originally used in PCR.

4. Taq polymerase Taq' s optimum temperature for  activity  is 75–80 °C, with a  half-life  of greater than 2 hours at 92.5 °C, 40 minutes at 95 °C and 9 minutes at 97.5 °C, and can replicate a 1000  base pair  strand of DNA in less than 10 seconds at 72 °C. One of  Taq' s drawbacks is its lack of  3'  to  5'   exonuclease   proofreading  activity resulting in relatively low replication fidelity. Originally its error rate was measured at about 1 in 9,000 nucleotides.

5. Thermus aquaticus is a gram negative, rod – shaped bacterium. It consists of a single polypeptide chain of molecular weight 95,000 daltons. It is resistant upto pH 9. 

6. function PCR involves denaturing, annealing and replication steps, usually repeated 20 to 30 times.  Denaturing separates the double-stranded DNA into single strands. In the annealing step, primers bind to the segments of DNA to be copied. Taq polymerase goes to work in the replication step: the polymerase builds each single strand of DNA marked by a primer into a new, double-stranded DNA segment.

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