Blast Sequence Alignment Tool: A Comprehensive Overview

Introduction

Blast (Basic Local Alignment Search Tool) is undoubtedly one of the most commonly used bioinformatics tools for comparison of biological sequences. The tool is extensively used in different domains ranging from molecular biology, biotechnology, drug discovery to systems biology. Blast alignment enables us to compare biological sequences to identify functional and evolutionary relationships between them. In this article, we will discuss the working, types, and applications of the Blast tool in detail.

Working Principle of Blast

The Blast algorithm searches for similarities in the sequence of nucleotides or amino acids by score-based alignments. The query sequence is compared with the target sequence, and a score is assigned for every alignment. A high score means a high level of similarity. Based on these scores, we can identify the best matching sequence. Blast performs two significant tasks; it finds the best possible match of the sequence, and it identifies regions of low sequence similarity between sequences.

Types of Blast

Blast is available in various versions based on the nature of sequence data and the types of analysis desired. The versions of Blast include:

• BLASTN: This version is used for nucleotide vs nucleotide searches.
• BLASTP: This version is used for protein vs protein searches.
• BLASTX: This version is used for nucleotide vs protein searches.
• TBLASTN: This version is used for a protein database search against a nucleotide database.
• TBLASTX: This version is used for a nucleotide database search against a protein database.

Apart from these versions, there are different types of Blast tools available depending on the specificity of the search, such as Psi-blast, Rps-blast, and so on.

Applications of Blast

Blast has diverse applications in various fields of biological sciences. Some of the primary applications of Blast include the following:

1. Genome Annotation: Blast is a valuable tool for genome annotation, including gene prediction and function identification.
2. Phylogenetic Analysis: Sequence similarity analysis provides useful information for phylogenetic analysis and constructing evolutionary trees.
3. Drug Discovery: Blast plays a critical role in drug development research. It can help identify targets for drug discovery and facilitate drug discovery by identifying homologous sequences to already known drug targets.
4. Protein Structure Prediction: Blast is widely used to analyze protein sequence data to predict protein structures.

Blast is a versatile and widely accessible tool that enables researchers to mine biological information from vast amounts of sequence data. Understanding the basics of Blast is crucial for conducting research in different fields of life sciences.