DNA synthesis of arbitrary sequences

Ransom Hill Bioscience visla at ix.netcom.com
Thu Jun 3 13:29:44 EST 1999


In article <7j6dvl$sbl$1 at news.spacelab.net>,
	"Zasha Weinberg" <zasha at nny.com> wrote:

>Some DNA synthesis methods allow us to generate oligonucleotides with
>arbitrary sequences up to some length (e.g. phosphoramidite chemistry, I
>think).  Does anyone know what the longest length is, for which some DNA
>synthesis method can synthesize an arbitrary sequence of that length?
>
>Thanks,
>
>-Z.
>
>
>

 Dear Zasha:

The maximum length of a synthesized oligo has two considerations. One is coupling efficiency,
limiting the maximum length to about 150 bases (yield is very poor, but you will get a small
amount of 150-mer). The second consideration is sequence fidelity, which begins to erode badly
around 90 bases in length, due to spurious chemical modifications to the bases resulting in
misreading. Since sequence fidelity is not an issue in a random sequence, the only consideration
is coupling efficiency. Be prepared to PAGE purify the oligo yourself, and ask the supplier to
"double couple" during synthesis, so as to increase the coupling efficiency to the maximum
possible. 

Best Regards,
Mike MacDonell, Ph. D.
Chief Scientific Officer
Ransom Hill Bioscience



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