the relationship between query sequence length and e-value/bit score in NCBI BLAST+
During a practice, I used 30 DNA query sequences in equal length (100bp). They are all from human genome.
After BLASTing them to the human reference genome, I saw an intersting result: although the sequences are totally different, the best match of each query always has the same e-value and bit score.
The e-values are always 2.67e-45
The bit-score are always 185
Since all the 30 DNA query sequences are completely different except they are in equal length, I guess whether the e-value and bit-score just depend on query sequence lengths? Is there any exact relationship rule or formular?
• 1,502 views
•
link
updated
by
Jean-Karim Heriche
•
written
by
bill-zt •
•
written
by
bill-zt •
1 answer
Read about the BLAST heuristics and associated statistics, for example:
• 0 views
•
link
written
by
Jean-Karim Heriche
Log in to answer this question.
More posts like this
-
How to conclude two genome sequences have the same origin?
written by Crunk •
-
BLAST e-value between two sequences vs BLAST e-value between sequence and data base
written by nyanovsky •
-
anomalous alignment with bowtie2
written by mark.rose •
-
sorting blast results by sseq coverage
written by nheb1977 •
-
Advice on Blast output
written by stacy734 •
-
Understanding Best-Hits filtering algorithm in BLAST+ applications
written by Denis
-
How to Determine the Most Conserved Sequence from BLAST Result?
written by Bahrani •
-
Distributed (parallel) BLAST. Calculating E-values and other statistics params.
written by vladimir.khramkov •
-
How is this blastresult possible?
written by ronaldnieuwenhuis •
-
E-Value In Blast
written by Beeth •
