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Poster Presentations
Day 2, June 23（Mon.）
Room P (Maesato East, Foyer, Ocean Wing)
- 2P-AM-16
The utility of combining two database search methods to identify phosphoserine and/or phosphothreonine in peptides in phosphoproteomics
(1BRC, Kobe Univ., 2ICMS, Med. Kobe Univ., 3Agric. Sci. Kobe Univ.)
oKen-ichi Yoshino1,2, Miyu Uehara3, Shuji Ueda3
Fragmentation during CID of phosphopeptides is complex, and this complexity cannot be covered by the simplicity of the methods used to detect O-phosphate groups as post-translational modifications in database searches. In fact, even without considering the neutral loss of phosphate groups, it is possible to identify many phosphorylated peptides and achieve high scores.
In this study, we compared the search results using the same LC/MS/MS data of a certain phosphopeptide mixture under the following three search conditions.
1) A method considering the neutral loss of phosphate groups, i.e., a method that calculates phosphoserine residue and phosphothreonine residue as dehydroalanine residue (69 Da) and dehydrobutyrine residue (83 Da), respectively.
2) A method in which the neutral loss of phosphate groups is ignored, i.e., a method that calculation is performed as phosphoserine residue (167 Da) and phosphothreonine (181 Da), respectively.
3) Use methods 1 and 2 together.
Although many phosphorylated peptides were identified by the searches using methods 1 and 2, a number of phosphopeptides could only be identified by method 3 . Therefore, we recommend performing database search using both methods together.