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Nov 28, 2023 · National Library of Medicine 8600 Rockville Pike Bethesda, MD 20894. The Basic Local Alignment Search Tool (BLAST) finds regions of local similarity between sequences. The program compares nucleotide or protein sequences to sequence databases and calculates the statistical significance of matches. BLAST can be used to infer functional and ...
Welcome to BLAST Help¶ Getting started¶ Quick start guide. Quick start results guide. Guide to BLAST home and search pages. Blast report description. Blast topics. Frequently Asked Questions. Getting Help¶ Write to the help desk. Mailing list. BLAST tutorials. About BLAST¶ NCBI Handbook. The Statistics of Sequence Similarity Scores. BLAST ...
PSI-BLAST allows the user to build a PSSM (position-specific scoring matrix) using the results of the first BlastP run. PHI-BLAST performs the search but limits alignments to those that match a pattern in the query. DELTA-BLAST constructs a PSSM using the results of a Conserved Domain Database search and searches a sequence database.
Nov 28, 2023 · The Basic Local Alignment Search Tool (BLAST) finds regions of local similarity between sequences. The program compares nucleotide or protein sequences to sequence databases and calculates the statistical significance of matches. BLAST can be used to infer functional and evolutionary relationships between sequences as well as help identify ...
The BLAST programs report E-value rather than P-values because it is easier to understand the difference between, for example, E-value of 5 and 10 than P-values of 0.993 and 0.99995. However, when E 0.01, P-values and E-value are nearly identical. Database searches
PSI-BLAST allows the user to build a PSSM (position-specific scoring matrix) using the results of the first BlastP run. PHI-BLAST performs the search but limits alignments to those that match a pattern in the query. DELTA-BLAST constructs a PSSM using the results of a Conserved Domain Database search and searches a sequence database.
The appropriate selection of a BLAST program for a given search is influenced by the following three factors 1) the nature of the query, 2) the purpose of the search, and 3) the database intended as the target of the search and its availability. The following tables provide recommendations on how to make this selection.
