It’s in the document
CHEM 402 Chemical Information Systems
Fall 2024
Homework 4
Wednesday, November 27, 2024, at 1:00 PM
To be submitted by 9:00 AM via BlackBoard
Get the protein sequences for human IRGM (Accession: NP_001139277.1) and the rat
IRGM (Accession: NP_001012007.1). You may use the Entrez Protein Search at the NCBI
website ( to fetch the sequences.
On the detailed protein information page, you may use the FASTA link at the top of the page
to get the sequences in the FASTA format. Compare the local alignment of these
sequences under dynamic programming. You may use the SIM tool by ExPasy
( to align the sequences.
a) (5 points) Note the effect of varying open and extended gap penalties on the alignment.
Report the top-5 local alignment scores obtained using BLOSUM62 on the following pair of
(open, extend) penalties: (12,12), (12,4), (12,1), (8,1), (4,1). Just write down the scores and
the lengths of the alignments; you do not need to show the actual alignment.
b) (5 points) Which pair of (open, extended) penalties given in part (a) corresponds to the
linear gap model?
c) (5 points) Now align the human IRGM to chimpanzee IRGM (Accession: XP_527077.1)
with the default parameters (BLOSUM62, Gap Open: 12, Gap Extend: 4). Compare this
alignment with that between human and rat IRGM (using same parameters) in terms of
length and score. Are the conserved sites between humans and mice also conserved
between humans and chimpanzees?