The methods utilized to determine the three dimensional structure of proteins are
The methods utilized to determine the three dimensional structure of proteins are
Select an option to attempt
Correct Answer: Option B
Explanation
BLOSUM (BLOcks SUbstitution Matrix) matrices are derived empirically from conserved blocks of aligned protein sequences. BLOSUM62 (most widely used) is calculated from proteins sharing ≤62% identity — substitution frequencies reflect evolutionary conservation. Matrix entries: positive scores = conservative substitutions (likely functionally equivalent); negative scores = disruptive substitutions. BLOSUM is used in: BLAST (Basic Local Alignment Search Tool); Smith-Waterman local alignments; profile HMMs for protein family detection. Contrast with PAM (Point Accepted Mutation) matrices, which are derived from closely related proteins and extrapolated. BLOSUM is generally preferred for detecting distant homologs and for database searching.