[BiO BB] Fwd: [blast-help] Refined nucleotide BLAST matrix
Yannick Wurm
idh at poulet.org
Wed Feb 23 03:25:18 EST 2005
And so this is the reference Peter mentioned, as kindly indicated by
Wayne Matten at NCBI.
@article{States1991Improved-Sensit,
Abstract = {Scoring matrices for nucleic acid sequence comparison that
are based on models appropriate to the analysis of molecular sequencing
errors or biological mutation processes are presented. In mammalian
genomes, transition mutations occur significantly more frequently than
transversions, and the optimal scoring of sequence alignments based on
this substitution model differs from that derived assuming a uniform
mutation model. The information from sequence alignments potentially
available using an optimal scoring system is compared with that
obtained using the BLASTN default scoring. A modified BLAST database
search tool allows these, or other explicitly specified scoring
matrices, to be utilized in computationally efficient queries of
nucleic acid databases with nucleic acid query sequences. Results of
searches performed using BLASTN's default score matrix are compared
with those using scores based on a mutational model in which
transitions are more prevalent than transversions.},
Author = {David J. States and Warren Gish and Stephen F. Altschul},
Date-Added = {2005-02-23 09:14:28 +0100},
Date-Modified = {2005-02-23 09:15:41 +0100},
Journal = {METHODS: A Companion to Methods in Enzymology},
Url = {http://blast.wustl.edu/doc/ntmats.pdf},
Month = {August},
Number = {1},
Pages = {66-70},
Title = {Improved Sensitivity of Nucleic Acid Database Searches Using
Application-Specific Scoring Matrices},
Volume = {3},
Year = {1991}}
Thanks again!
-yannick
Begin forwarded message:
> From: "Matten, Wayne (NIH/NLM)"
> Date: 22 février 2005 21:23:29 GMT+01:00
> To: 'Yannick Wurm' <Yannick.Wurm at unil.ch>,
> "'blast-help at ncbi.nlm.nih.gov'" <blast-help at ncbi.nlm.nih.gov>
> Subject: RE: [blast-help] Refined nucleotide BLAST matrix
>
> Hello,
>
> I believe the reference that Peter mentions is this one:
>
> http://blast.wustl.edu/doc/ntmats.pdf
>
> Peter summed up the "hack" very well. You might need other commandline
> options; turning off the low complexity filter comes to mind. But you
> can get blastp, within blastall, to run as long as you format the
> database as a protein database and use a matrix name already in the
> /data directory. You might also get some ideas from here:
>
> ftp://ftp.ncbi.nlm.nih.gov/blast/matrices/
>
> e.g., NUC4.4.
>
>
> Best regards,
> Wayne
>
> <><><><>>><>>>>><><>>><>
> Wayne Matten
> NCBI User Services
. . . . . . . . . . . . . . . . . .
yannick.wurm at unil.ch
+41.21.692.4157
PhD student, Departement of Ecology and Evolution
Université de Lausanne, Switzerland
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