Single-worm quantitative proteomics reveals aging heterogeneity in isogenic Caenorhabditis elegans.

The heterogeneity of aging has been investigated at cellular and organic levels in the mouse model and human, but the exploration of aging heterogeneity at whole-organism level is lacking. C. elegans is an ideal model organism for studying this question as they are self-fertilized and cultured in the same chamber.

Mapping protein direct interactome of oxidoreductases with small molecular chemical cross-linkers in live cells.

Identifying direct substrates of enzymes has been a long-term challenge. Here, we present a strategy using live cell chemical cross-linking and mass spectrometry to identify the putative substrates of enzymes for further biochemical validation. Compared with other methods, our strategy is based on the identification of cross-linked peptides supported by high-quality MS/MS spectra, which eliminates false-positive discoveries of indirect binders.

Detecting Active Deconjugating Enzymes with Genetically Encoded Activity-Based Ubiquitin and Ubiquitin-like Protein Probes.

Post-translational modification of proteins by Ubiquitin (Ub) and Ubiquitin-like proteins (Ubls) can be reversed by deconjugating enzymes, which have been implicated in different pathways and associated with various human diseases. To understand the activity and dynamics of deconjugating enzymes, multiple synthetic and semi-synthetic Ub/Ubl probes have been developed, and some of them have been applied to screen inhibitors of deconjugating enzymes. Since these Ub/Ubl probes are generally not cell-permeable, different strategies have been developed to deliver Ub/Ubl probes to live cells.

Corrigendum: Proteome and Acetyl-Proteome Profiling of cv. 'Anji Baicha' during Periodic Albinism Reveals Alterations in Photosynthetic and Secondary Metabolite Biosynthetic Pathways.

[This corrects the article on p. 2104 in vol. 8, PMID: 29312376.

Proteome and Acetyl-Proteome Profiling of cv. 'Anjin Baicha' during Periodic Albinism Reveals Alterations in Photosynthetic and Secondary Metabolite Biosynthetic Pathways.

Tea leaf color is not only important from an aesthetics standpoint but is also related to tea quality. To investigate the molecular mechanisms that determine tea leaf color, we examined cv. 'Anjin Baicha' (an albino tea cultivar) by tandem mass tag isobaric labeling to generate a high-resolution proteome and acetyl-proteome atlas of three leaf developmental stages.

A new sample preparation method for the absolute quantitation of a target proteome using (18)O labeling combined with multiple reaction monitoring mass spectrometry.

A key step in the workflow of bottom-up proteomics is the proteolysis of proteins into peptides with trypsin. In addition, enzyme-catalytic (18)O labeled peptides as internal standards coupled with multiple reaction monitoring mass spectrometry (MRM MS) for the absolute quantitation of the target proteome is commonly used for its convenient operation and low cost. However, long digestion and labeling times, incomplete digestion and (18)O to (16)O back exchange limit its application, therefore, we developed a rapid and efficient digestion method based on a high ratio of trypsin to protein.

[Metal-tag labeling coupled with high performance liquid chromatography-selected ion monitoring mass spectrometry for absolute quantitation of proteins].

A novel method has been established based on metal element chelated tags coupled with high performance liquid chromatography-selected ion monitoring mass spectrometry (HPLC-SIM/MS). The labeling efficiency and stability of metal element chelated tags, the chromatographic retention behavior and MS behavior of the labeled peptides, the linear range and accuracy of this method were examined. The results showed that the metal element chelated tag method has high labeling efficiency and high labeling stability, and the labeled peptides with different kinds of metal tags have consistent chromatographic retention behavior.

[A novel method for absolute protein quantification using 18O isotope labeled concatamers of Q peptides combined with isotope dilution-multiple reaction monitoring mass spectrometry].

A method of concatamers of Q peptides (QconCATs) protein labeled with 18O-multiple reaction monitoring mass spectrometry for absolute quantification of proteins is established. The purity of the QconCAT recombinant protein was characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), and its purity was above 99%. The relative molecular mass was approximately 63.

[Preparation of a trypsin immobilized reactor on silver wire modified by atom transfer radical polymer and its application in proteome identification].

The routine proteolysis of proteins is performed in solution, but it suffers from drawbacks such as long incubation time, enzyme autodigestion, and non-reusability. Therefore we here demonstrated that trypsin could be immobilized on silver wire modified by atom transfer radical polymerization to prepare a new kind of enzyme immobilized reactor. The digestion efficiency, repeatability and recovery of the silver wire-trypsin reactor (SW-Trypsin) were evaluated by mass spectrometry (MS) analysis.

[Effects of the size of magnetic particles of immobilized enzyme reactors on the digestion performance].

We applied immobilized enzyme reactors prepared with different sizes of magnetic particles into protein and proteome digestion. In addition, the influences of different sizes of the magnetic particles were studied on the reunion, enzyme efficiency and leakage sites. The experimental results showed that in comparison with the submicron magnetic particles, the amount of trypsin immobilized on the magnetic nanoparticles was 3.

[Establishment of retention time-dependent intelligent selected reaction monitoring mass spectrometric method and its application].

A method of liquid chromatographic retention time-dependent intelligent selected reaction monitoring mass spectrometry (iSRM MS) was established for the identification of targeted proteome, and was compared in detail with the method without liquid chromatographic retention time-dependent iSRM MS in the analysis results of different samples, such as the peptide mixtures from bovine serum albumin, six standard proteins or Thermoanaerobacter tengcongensis extract digested by trypsin. The results showed that the throughput of the identified peptides and the proteins was evidently increased with the method of liquid chromatographic retention time-dependent iSRM MS, especially in the complex sample such as Thermoanaerobacter tengcongensis extract. The coverage of the identified peptides and proteins from Thermoanaerobacter tengcongensis extract was reached 89.