Restriction enzyme help

Peter Rice rice at
Sun Apr 4 17:28:44 EST 1993

In article <nash.88.0 at>, nash at (John Nash) writes:
> In article <1993Apr2.181617.15803 at> abigail at (Shawn Abigail) writes:
>>I downloaded a file with a list of restriction enzymes, their sequences
>>and sources.  I am a little confused over the nomenclature of the sequences.
>>C, T, A & G are obvious!  R stands for a Purine and Y stands for a
>>Pyrimidine.  Does N stand for "any nucleotide"?  What about W and S?
>>Any help is gratefully appreciated.
>                        Mnemonic
> R = A or G	         puRine
> Y = T or C             pYrimidine
> W = A or T	         Weak (2-bonds)
> S = G or C             Strong (3-bonds)
> M = A or C	         aMino group
> K = G or T             Keto group
> B = C or T or G        not-A
> D = A or G or T        not-C
> H = A or T or C        not-G
> V = A or C or G        not-(T or U)
> N = A or C or G or T   aNy

also: X = unknown (could be Inosine, etc.)
      U = T       (DNA and RNA sequences are "the same")

I added the explanations for the names to thr right of the message above.
Curiously, the 3-letter codes are actually easier than the 2-letter codes.

 Peter Rice, EMBL                             | Post: Computer Group
                                              |       European Molecular
 Internet:    Peter.Rice at EMBL-Heidelberg.DE   |            Biology Laboratory
                                              |       Postfach 10-2209
 Phone:   +49-6221-387247                     |       W-6900 Heidelberg
 Fax:     +49-6221-387306                     |       Germany

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