Abstract
Unexpected tryptic cleavage has been characterized at modified K48 residues in polyubiquitins. In particular, the tryptic products of all seven of the lysine-linked dimers of ubiquitin and of three trimers-linear Ub-48Ub-48Ub, linear Ub-63Ub-63Ub, and the branched trimer [Ub]2-6,48Ub-have been analyzed. In addition to the peptide products expected under commonly used tryptic conditions, we observe that peptides are formed with an unexpected ε-glycinylglycinyl-Lys carboxyl terminus when the site of linkage is Lys48. Trypsin from three different commercial sources exhibited this aberration. Initial cleavage at R74 is proposed in a distal ubiquitin to produce a glycinylglycinyl-lysine residue which is bound by trypsin.
Original language | English (US) |
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Pages (from-to) | 8144-8148 |
Number of pages | 5 |
Journal | Analytical Chemistry |
Volume | 87 |
Issue number | 16 |
DOIs | |
State | Published - Aug 18 2015 |
Externally published | Yes |
ASJC Scopus subject areas
- Analytical Chemistry