title: Study of the preferred modification sites of the quinone methide intermediate resulting from the latent trapping device of the activity probes for hydrolases.
abstract: Use of activity probes has been demonstrated to be a powerful tool in modern chemical proteomic study. Previously we have designed and synthesized a series of mechanism-based activity probes that utilized quinone methide chemistry. Here, we characterized the trend of chemical reactivity for the reactive quinone methide intermediate 3 (QM-3) resulting from the latent trapping device. In a competition assay, the labeling of PTP1B by probe 1a was blocked by externally added cysteine without affecting the catalytic activity of the enzyme. Further sequencing analysis on the trypsin-digested peptides of probe 1a-labeled PTP1B using tandem mass spectrometry revealed that all six cysteine residues of PTP1B are capable of being modified by probe 1a. These results indicated that the sulfhydryl group of cysteine residue is the preferred nucleophile for the reactive QM-3. Our finding provides the first example in understanding the preferred amino acid residues modified by the reactive QM-3, which is also the key structural unit responsible for forming covalent bonds in many biochemical applications.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 106, Taiwan. lclo@ntu.edu.tw
authors.forename: Lee-Chiang
authors.initials: LC
authors.lastname: Lo
authors.forename: Ying-Ling
authors.initials: YL
authors.lastname: Chiang
authors.forename: Chi-Hsien
authors.initials: CH
authors.lastname: Kuo
authors.forename: Hsin-Kai
authors.initials: HK
authors.lastname: Liao
authors.forename: Yu-Ju
authors.initials: YJ
authors.lastname: Chen
authors.forename: Jing-Jer
authors.initials: JJ
authors.lastname: Lin
mesh_terms: D001665:Binding Sites; D004789:Enzyme Activation; D020869:Gene Expression Profiling / Q000379:methods*; D006801:Humans; D006867:Hydrolases / Q000737:chemistry; D045563:Indolequinones / Q000032:analysis / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D015335:Molecular Probes / Q000737:chemistry*; D011485:Protein Binding; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry*; D040901:Proteomics / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods*; D013329:Structure-Activity Relationship
chemical_list: D045563:Indolequinones; D015335:Molecular Probes; C068040:quinone methide; D006867:Hydrolases; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases