16S PCR product to short

[felipe wettstein]

hello

we do PCR with the primerpair 1522r and 27f (E.coli positions), but the
product size is only about 500bp, instead of 1500bp. this problem we
have only in the last few weeks. the phenomen correlates with a new taq
we are using. could this be a reason? or the new buffer of this taq
(looks like buffers use to look like)??

annealing is 10 times at 60C for 30sec
and          15 times at 53C for 30sec

before we used different taqs, most usually gibco, endconcentration
2U/100ul reaction
now we are using amersham pharmacia, taq dna polymerase, also at
2U/100ul reaction

thank you very much for suggestions

felipe


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