BLAST
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| - | BLAST (Basic Local Alignment Search Tool) is an algorithm for comparing biological sequences, such as amino-acid sequences or nucleotides sequences. | + | BLAST (Basic Local Alignment Search Tool) is an algorithm for comparing biological sequences, such as amino-acid sequences or nucleotides sequences. Through a ''BLAST search'' a researcher can compare a ''query'' sequence with a ''library'' (database) of sequences, and identify library sequences that are similar to the query sequence above a certain threshold. |
| - | + | ||
| - | Through a ''BLAST search'' a researcher can compare a ''query'' sequence with a ''library'' (database) of sequences, and identify library sequences that are similar to the query sequence above a certain threshold. | + | |
| + | The NCBI BLAST (version 2.2.12) is installed on the [[cluster]] machine, together with the most famous sequence libraries (such as EMBL, UNIPROT), which are automatically updated every night. The local installation of BLAST and relative libraries allow to customize and speed up sequence analysis, such as in automatic annotation of sequence projects. | ||
| - | ===Programs=== | + | === How to reach BLAST === |
| + | BLAST can be launched by clicking [http://bioinfo.ceinge.unina.it/tools/winterf/blast2.php here] . | ||
| + | BLAST utilities can be searched and launched from the [http://bioinfo.ceinge.unina.it Bioinfo website] through the [[PROGsDB]]. | ||
| + | Blastall can be also launched by [[CAPRI]]. | ||
| + | |||
| + | In the [[VLS]] environment, the BLAST package is fully available for command line use in the directory ''/bioprogs/blast''. The blastable libraries are located in the directory ''/biodata/dbs/blast''. | ||
| + | |||
| + | ===Available Programs=== | ||
| The BLAST programs can be run by the command-line utilities. <br>'''Blastall''' is probably the most famous utility and includes a family of algorithms, such as: | The BLAST programs can be run by the command-line utilities. <br>'''Blastall''' is probably the most famous utility and includes a family of algorithms, such as: | ||
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| A more detailed description of each BLAST utility available [http://bioinfo.ceinge.unina.it/help/blast/ here] | A more detailed description of each BLAST utility available [http://bioinfo.ceinge.unina.it/help/blast/ here] | ||
| - | === How to reach and use BLAST === | ||
| - | BLAST utilities can be searched and launched from the [http://bioinfo.ceinge.unina.it Bioinfo website] through the [[PROGsDB]]. | ||
| - | Blastall can be also launched by [[CAPRI]]. | ||
| - | |||
| - | In the [[VLS]] environment, the BLAST package is fully available for command line use in the directory ''/bioprogs/blast''. The blastable libraries are located in the directory ''/biodata/dbs/blast''. | ||
| === References === | === References === | ||
Revision as of 10:22, 20 June 2007
BLAST (Basic Local Alignment Search Tool) is an algorithm for comparing biological sequences, such as amino-acid sequences or nucleotides sequences. Through a BLAST search a researcher can compare a query sequence with a library (database) of sequences, and identify library sequences that are similar to the query sequence above a certain threshold.
The NCBI BLAST (version 2.2.12) is installed on the cluster machine, together with the most famous sequence libraries (such as EMBL, UNIPROT), which are automatically updated every night. The local installation of BLAST and relative libraries allow to customize and speed up sequence analysis, such as in automatic annotation of sequence projects.
How to reach BLAST
BLAST can be launched by clicking here . BLAST utilities can be searched and launched from the Bioinfo website through the PROGsDB. Blastall can be also launched by CAPRI.
In the VLS environment, the BLAST package is fully available for command line use in the directory /bioprogs/blast. The blastable libraries are located in the directory /biodata/dbs/blast.
Available Programs
The BLAST programs can be run by the command-line utilities.
Blastall is probably the most famous utility and includes a family of algorithms, such as:
- blastp : compares an amino acid query sequence against a protein sequence database
- blastn : compares a nucleotide query sequence against a nucleotide sequence database
- blastx : compares a nucleotide query sequence translated in all reading frames against a protein sequence database
- tblastn : compares a protein query sequence against a nucleotide sequence database dynamically translated in all reading frames
- tblastx : compares the six-frame translations of a nucleotide query sequence against the six-frame translations of a nucleotide sequence database.
Other advanced utilities are also available:
- bl2seq : compares two sequences using one of the same blastall algorithms described above;
- megablast: compares highly similar nucleotide sequences by concatenating many input sequences together to form a large sequence before searching the BLAST database;
- Blastpgp : perform iterative searches, in two different modes:
- psi-blast : an iterative search in which sequences found in one round of searching are used to build a score model for the next round of searching.
- phi-blast : combines matching of regular expressions with local alignments surrounding each identified match.
A more detailed description of each BLAST utility available here
References
Altschul SF, Stephen F, Madden TL, Schäffer AA, Zhang J, Zhang Z, Miller W and David J. Lipman DJ Gapped BLAST and PSI-BLAST: a new generation of protein database search programs, Nucleic Acids Res., 1997, 25:3389-3402.
For more details about NCBI BLAST, visit the BLAST web site
