Purpose I: To understand the common errors in de novo sequencing.

1. Download the following data files:

Iontrap1, Iontrap2, Iontrap3

2. Use the server at bioinfor.com/peaksonline to do de novo sequencing.

3. Compare the de novo sequencing results with the correct sequence (in the file name).

4. Examine the same mass replacement errors.

5. Use SPIDER (http://bif.csd.uwo.ca/spider/) to find the correct sequence.

Purpose II: Browse unimod PTM database.

1. Go to unimod PTM database. http://unimod.org/login.php?message=expired

2. Try to understand the usage of unimod.

3. Try some other PTM databases.

Purpose III: Check out another MS/MS database search software. http://thegpm.org