The following is only a partial list of products available commercially for the PCR, and the inclusion or exclusion of any enzyme does not indicate approval or disapproval. While we believe these facts to be essentially correct, potential users should consult the technical literature from the supplier of any enzyme before purchase or use.

PE Applied Biosystems

Amplitaqrecombinant from Thermus aquataicus; t1/2 40 min at 95C; 5->3' nuclease; 50 nt processivity

Amplitaq LDvery low bacterial DNA contamination (<4 copies of 16S RNA sequences / unit)

Amplitaq Goldbecomes active only after first high temperature cycle (due to addition of antibody), thus suppressing products from nonspecific primer hybridization at low temperature.

Amplitaq Stoffel fragment289 aa have been deleted from the N-terminal end, eliminating the 5->3' nuclease activity; it is active over a wide range of Mg++ concentration, which enables amplification from multiple primers in the same reaction; about 2X as thermostable as the full length polymerase.

rT threcombinant from Thermus thermophilus; has reverse transcriptase activity (producing DNA from an RNA template) with Mn++ , as well as DNA polymerase activity. Thus it can produce DNA copies from RNA in one step. 20 min t 1/2 at 95C .

rT th XLa mix of rT th and the DNA polymerase from Thermococcus litoralis; the resulting 3->5' proofreading nuclease activity and formulation enable production of long DNA copies (>40 kb).

MJ Research as distributer for Finnzymes Oy

DyNAzyme EXTrecombinant from Thermus brockianus; t 1/2 200 min at 95C; 3->5' proofreading nuclease activity ; can produce copies of >40 kb length.

New England Biolabs

Ventrecombinant from Thermococcus litoralis; t 1/2 400 min at 95C ; enzymes with and without 3->5' proofreading exonuclease activity available; can produce copies >15 kb in length.

Deep Ventrecombinant from Pyrococcus GB-D; t 1/2 23 hours at 95C; enzymes with and without 3->5' proofreading exonuclease activity available; can produce copies >15 kp in length.