Unexpected Trypsin Cleavage at Ubiquitinated Lysines

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• 作者：Meghan C. Burke ; Yan Wang ; Amanda E. Lee ; Emma Kimm Dixon ; Carlos A. Castaneda ; David Fushman ; Catherine Fenselau
• 刊名：Analytical Chemistry
• 出版年：2015
• 出版时间：August 18, 2015
• 年：2015
• 卷：87
• 期：16
• 页码：8144-8148
• 全文大小：284K
• ISSN：1520-6882

文摘

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鈥攍inear Ub鈥?sup>48Ub鈥?sup>48Ub, linear Ub鈥?sup>63Ub鈥?sup>63Ub, and the branched trimer [Ub]₂鈥?sup>6,48Ub鈥攈ave been analyzed. In addition to the peptide products expected under commonly used tryptic conditions, we observe that peptides are formed with an unexpected 蔚-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.