BLASTP Short peptide sequences 8-15 aa long- What is an appropriate E-value cut-off?

28 March 2024 0 7K Report

I am blast-searching various peptide sequences, mostly between 8-15 aa long. I am new to blast searching and have no idea what sort of cut-off threshold to use to determine significance. The search parameters were automatically adjusted for a short input sequence, creating a word size of 2 and Expect value 200000, however I then don't know how to interpret these as significant vs insignificant, as I have read it is different for longer peptides above 30 aas where people recommend values such as 1e-6. Any advice would be of great help!

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