BLOSUM

From Wikipedia, the free encyclopedia

BLOSUM (BLOcks SUbstitution Matrix) is a substitution matrix used for sequence alignment of proteins. BLOSUM matrices are used to score alignments between evolutionarily divergent protein sequences. They were first introduced in a paper by Henikoff and Henikoff (1992; PNAS 89:10915-10919). They scanned the BLOCKS database for very conserved regions of protein families (that do not have gaps in the sequence alignment) and then counted the relative frequencies of amino acids and their substitution probabilities. Then, they calculated a log-odds score for each of the 210 possible substitutions of the 20 standard amino acids. BLOSUM62 is the matrix calculated by using the observed substitutions between proteins which have 62% or more^[1] sequence identity. BLOSUM has proved better at scoring distantly related sequences than the once-widely-used Point Accepted Mutation (PAM) matrices.

[edit] References

[edit] See also

• Sequence alignment
• Percent accepted mutation

This bioinformatics-related article is a stub. You can help Wikipedia by expanding it.