[Biopython] NCBIWWW.qblast Expect value / E-value

Jasper Koehorst jasperkoehorst at gmail.com
Wed May 20 12:51:13 UTC 2009


Im running against problems when i try to identify short peptide sequences
of ±10 - 20 peptides. When i run this at the NCBI Blast website i get
results, these all have
high E-Values that i dont really care at the moment. The problem is when i
do this in biopython as stated below, i will not get any results...

I believe this is due to the fact that biopython will not show results with
a "high" E-Value. Is there a way to change this? So it will allow results
with an E-value of ±1500
or more?

I tried the sript below but that does not quit work...

Anybody has an idea?

        result_handle =
NCBIWWW.qblast("blastp","nr",peptide[1],entrez_query=i, expect=2000,
matrix_name='BLOSUM80')
        blast_records = NCBIXML.parse(result_handle)
        blast_record = blast_records.next()
        E_VALUE_TRESH = 10000000
        for alignment in blast_record.alignments:
            for hsp in alignment.hsps:




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