Taq+Polymerase

= Taq Polymerase =

General information
toc


 * ~ Name Origin ||<  Thermostable DNA Polymeras e isolate d from an // Thermus aquaticus (Taq). // ||


 * ~ Discoverers || Thomas D. Brock and Hudson Freeze ||
 * ~ Patent holders || Hoffmann-La Roche ||

...and more ||
 * ~ Main Areas of Application || * PCR,
 * RT-PCR,
 * DNA sequencing,
 * 3'' A.tailing of blunt ends
 * ~ Market Size || $3,950.00 (US$) per year, at 4th Jan 2008 ||

This is an enzyme that can add nucleotides (dNTP's) and form a double-stranded DNA sequence based on a single-stranded DNA sequence template.

Taq Polymerase is a stable deoxyribonucleic acid (DNA) polymerase (EC 2.7.7.7) with an optimum temperature of 80 degrees C that has been purified from the extreme thermophile bacterium //Thermus aquaticus//. The enzyme is free from phosphomonoesterase, phosphodiesterase and single-stranded exonuclease activities. Maximal activity of the enzyme requires all four deoxyribonucleotides and activated calf thymus DNA and an absolute requirement for divalent cation cofactor (satisfied by Mg2+ or in less extent by Mn2+). Monovalent cations at concentrations as high as 0.1 M did not show a significant inhibitory effect. The optimum pH was 8.0 in tris(hydroxymethyl)aminomethane-hydrochloride buffer (Tris-HCl). The molecular weight of the enzyme was estimated by sucrose gradient centrifugation and gel filtrations on Sephadex G-100 to be approximately 63,000 to 68,000. The elevated temperature requirement, small size, and lack of nuclease activity distinguish this polymerase from the DNA polymerase of Escherichia coli ( Klenow fragment).

History
1986 - First forensic use of Taq Polymerase. 1989 - The first cloned recombinant Taq DNA polymerase (AmpliTaq) is introduced.
 * 1965** - Isolation from a thermophilic bacterium named //Thermus aquaticus// by Thomas D. Brock and his colleague Hudson Freeze.
 * 1976, September** - Alice Chien and John M.Trela publish at the Journal of Bacteriology an article about the characterization of Taq Polymerase.
 * 1986** - Klenow fragment is replaced for the first time by Taq polymerase in PCR.
 * 1989,January 19** - Announcement of PCR and Taq patents buying by Hoffmann-La Roche from Cetus for about $330 million. They approximately received $2 billion in royalties from it.
 * 1989** - The first "Molecule of the Year" is Taq Polymerase.The name is awarded by Science Magazine.
 * early 1990's** - Taq Polymerase meets application trought PCR in areas such as basic molecular biology research, clinical testing, forensics and more. HIV virus direct detection in AIDS also becomes being done with this technique.
 * 1991** - Technology allowing simultaneous amplification and detection of genetic material found in TaqMan® tests has it first publication.
 * 1993** - The first and unique Nober Prize awarded to a company from the biotechnological field is delivered to Kary Mullis, from Cetus Corporatrion of Emeryville, California.
 * 1995** - The enzyme responsible for the Human Genome sequencing (AmpliTaq DNA polymerase FS) is introduced in scientific field.

Applications & Financial Information
It is dificult to tell apart the PCR applications and those from Taq Polymerase. Although, the table below summarizes of the main applications of four diferent polymerase types. Relatively to the financial information, prices vary with specificity, concentration and company that supplies it. This can also be seen in the table. Definition of U: One unit (U) of the enzyme catalyzes the incorporation of 10 nmol of deoxyribonucleotides into a polynucleotide fraction in 30 min at 70°C.

Taq Polymerase Variations
The original Taq Polymerase does not have the sensitivity or specificity required for some applications, where is needed less nonspecific amplification products, primer-dimers, and/or background. In order to accomplish that level of sensitivity or specificity, many types of Taq Polymerase have been constructed over the years, trough biotechnological tools. For the same specification Taq Polymerase, companies name them differently. The table below shows some of those types (the most used ones) and their characteristics.