Computing H/D-Exchange rates of single residues from data of proteolytic fragments

<p>Abstract</p> <p>Background</p> <p>Protein conformation and protein/protein interaction can be elucidated by solution-phase Hydrogen/Deuterium exchange (sHDX) coupled to high-resolution mass analysis of the digested protein or protein complex. In sHDX experiments mutant proteins are compared to wild-type proteins or a ligand is added to the protein and compared to the wild-type protein (or mutant). The number of deuteriums incorporated into the polypeptides generated from the protease digest of the protein is related to the solvent accessibility of amide protons within the original protein construct.</p> <p>Results</p> <p>In this work, sHDX data was collected on a 14.5 T FT-ICR MS. An algorithm was developed based on combinatorial optimization that predicts deuterium exchange with high spatial resolution based on the sHDX data of overlapping proteolytic fragments. Often the algorithm assigns deuterium exchange with single residue resolution.</p> <p>Conclusions</p> <p>With our new method it is possible to automatically determine deuterium exchange with higher spatial resolution than the level of digested fragments.</p

Photoactivatable probes and uses thereof

Provided herein are pyridyl- and pyrimidyl-containing diazirines that can be photoactivateable probes and formulations thereof. Also provided herein are photoaffinity labels that can include the pyridyl- and pyrimidyl-containing diazirines provided herein. Also provided herein are methods of using the photoactivatable probes and photoaffinity labels provided herein in a photoaffinity labeling reaction and/or assay

Site-specific human histone H3 methylation stability: fast K4me3 turnover

We employ stable‐isotope labeling and quantitative mass spectrometry to track histone methylation stability. We show that H3 trimethyl K9 and K27 are slow to be established on new histones and slow to disappear from old histones, with half‐lives of multiple cell divisions. By contrast, the transcription‐associated marks K4me3 and K36me3 turn over far more rapidly, with half‐lives of 6.8 h and 57 h, respectively. Inhibition of demethylases increases K9 and K36 methylation, with K9 showing the largest and most robust increase. We interpret different turnover rates in light of genome‐wide localization data and transcription‐dependent nucleosome rearrangements proximal to the transcription start site

Target binding molecules identified by kinetic target-guided synthesis

Methods of identifying target binding molecules by target guided synthesis are provided. The methods include providing two or more fragments capable of reacting to form the target binding molecule and mixing the fragments with the target. The methods can be used to identify target binding molecules that bind targets such as proteins or nucleic acids, including those that bind shallow binding pockets on the surface of such targets. The methods are applied to the Bcl-XL and Mcl-1 proteins from the Bcl-2 family of proteins. Using thio acid and sulfonyl azide fragments capable of reacting through sulfo-click chemistry, new acyl sulfonamides are identified that bind one or both of the Bcl-XL and Mcl-1 proteins. Pharmaceutical formulations of these target binding molecules are also provided

Going beyond Binary: Rapid Identification of Protein–Protein Interaction Modulators Using a Multifragment Kinetic Target-Guided Synthesis Approach

Kinetic target-guided synthesis (KTGS) is a powerful screening approach that enables identification of small molecule modulators for biomolecules. While many KTGS variants have emerged, a majority of the examples suffer from limited throughput and a poor signal/noise ratio, hampering reliable hit detection. Herein, we present our optimized multifragment KTGS screening strategy that tackles these limitations. This approach utilizes selected reaction monitoring liquid chromatography tandem mass spectrometry for hit detection, enabling the incubation of 190 fragment combinations per screening well. Consequentially, our fragment library was expanded from 81 possible combinations to 1710, representing the largest KTGS screening library assembled to date. The expanded library was screened against Mcl-1, leading to the discovery of 24 inhibitors. This work unveils the true potential of KTGS with respect to the rapid and reliable identification of hits, further highlighting its utility as a complement to the existing repertoire of screening methods used in drug discovery

Robust Analysis of the Yeast Proteome under 50 kDa by Molecular-Mass-Based Fractionation and Top-Down Mass Spectrometry

As the process of top-down mass spectrometry continues to mature, we benchmark the next installment of an improving methodology that incorporates a tube-gel electrophoresis (TGE) device to separate intact proteins by molecular mass. Top-down proteomics is accomplished in a robust fashion to yield the identification of hundreds of unique proteins, many of which correspond to multiple protein forms. The TGE platform separates 0–50 kDa proteins extracted from the yeast proteome into 12 fractions prior to automated nanocapillary LC–MS/MS in technical triplicate. The process may be completed in less than 72 h. From this study, 530 unique proteins and 1103 distinct protein species were identified and characterized, thus representing the highest coverage to date of the Saccharomyces cerevisiae proteome using top-down proteomics. The work signifies a significant step in the maturation of proteomics based on direct measurement and fragmentation of intact proteins

Going beyond Binary: Rapid Identification of Protein–Protein Interaction Modulators Using a Multifragment Kinetic Target-Guided Synthesis Approach

Kinetic target-guided synthesis (KTGS) is a powerful screening approach that enables identification of small molecule modulators for biomolecules. While many KTGS variants have emerged, a majority of the examples suffer from limited throughput and a poor signal/noise ratio, hampering reliable hit detection. Herein, we present our optimized multifragment KTGS screening strategy that tackles these limitations. This approach utilizes selected reaction monitoring liquid chromatography tandem mass spectrometry for hit detection, enabling the incubation of 190 fragment combinations per screening well. Consequentially, our fragment library was expanded from 81 possible combinations to 1710, representing the largest KTGS screening library assembled to date. The expanded library was screened against Mcl-1, leading to the discovery of 24 inhibitors. This work unveils the true potential of KTGS with respect to the rapid and reliable identification of hits, further highlighting its utility as a complement to the existing repertoire of screening methods used in drug discovery