Introduction

Basic Local Alignment Search Tool (BLAST) is an analysis tool used for similarity comparison in the protein database or DNA database. The BLAST program can quickly find the similarity between the object sequence and that recorded in public databases. The score in the BLAST result is a statistical description of similarity.

BLAST uses a local algorithm to obtain sequences that are similar in two sequences.

BLAST compares one or more sequences (in any form) To one or more nucleic acid or protein sequence libraries. BLAST can also find sequences with matched gaps.

Based on the method published by Altschul et al. on J. Mol. Biol (J. Mol. Biol. 215: 403-410 (1990)), BLAST checks/analyzes the homology between queried sequences and those recorded in sequence databases. Compared with the initial BLAST, BLAST 2.0 provided by NCBI adopts gap penalty in sequence alignment. BLAST can process any number of sequences, including protein sequences and nucleic acid sequences. Multiple databases of the same type can be selected, that is, either all protein databases or all nucleic acid databases. The queried sequence and the invoked database may be a combination of any form. You can analyze a nucleic acid sequence or protein sequence with a protein or nucleic acid database.

Software packages such as GCG and EMBOSS contain five types of BLAST:

• BLASTP is used to query protein sequences in protein databases. It compares each queried sequence with each sequence recorded in databases one by one.
• BLASTX is used to query nucleic acid sequences in protein databases. First, it translates the nucleic acid sequence into a protein sequence (translates one nucleic acid sequence into six possible proteins), and then performs a one-to-one protein sequence comparison on each of the protein sequences.
• BLASTN is used to query nucleic acid sequences in nucleic acid databases. It compares each known sequence in databases with each queried nucleic acid sequence one by one.
• TBLASTN is used to query protein sequences in nucleic acid databases. In contrast to BLASTX, it translates nucleic acid sequences in databases into protein sequences, and then compares them with the queried sequences.
• TBLASTX is used to query nucleic acid sequences in nucleic acid databases. It translates both the nucleic acid sequences in databases and the queried nucleic acid sequences into proteins (each nucleic acid sequence produces six possible protein sequences), which produces 36 comparison arrays each time.

For more information, visit the official BLAST website.

Programming language: C++

Brief description: An analysis tool used for similarity comparison in the protein database or DNA database.

Open source license: PUBLIC DOMAIN