Unexpected Trypsin Cleavage at Ubiquitinated Lysines

Meghan C. Burke, Yan Wang, Amanda E. Lee, Emma Kimm Dixon, Carlos A. Castaneda, David Fushman, Catherine Fenselau

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


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 languageEnglish (US)
Pages (from-to)8144-8148
Number of pages5
JournalAnalytical Chemistry
Issue number16
StatePublished - Aug 18 2015
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry


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