Correction to "Assessing Physicochemical Properties of Drug Molecules via Microsolvation Measurements with Differential Mobility Spectrometry".

[This corrects the article DOI: 10.1021/acscentsci.6b00297.

Assessing Physicochemical Properties of Drug Molecules via Microsolvation Measurements with Differential Mobility Spectrometry.

The microsolvated state of a molecule, represented by its interactions with only a small number of solvent molecules, can play a key role in determining the observable bulk properties of the molecule. This is especially true in cases where strong local hydrogen bonding exists between the molecule and the solvent. One method that can probe the microsolvated states of charged molecules is differential mobility spectrometry (DMS), which rapidly interrogates an ion's transitions between a solvated and desolvated state in the gas phase (i.

Chemical and computational methods for the characterization of covalent reactive groups for the prospective design of irreversible inhibitors.

Interest in drugs that covalently modify their target is driven by the desire for enhanced efficacy that can result from the silencing of enzymatic activity until protein resynthesis can occur, along with the potential for increased selectivity by targeting uniquely positioned nucleophilic residues in the protein. However, covalent approaches carry additional risk for toxicities or hypersensitivity reactions that can result from covalent modification of unintended targets. Here we describe methods for measuring the reactivity of covalent reactive groups (CRGs) with a biologically relevant nucleophile, glutathione (GSH), along with kinetic data for a broad array of electrophiles.

Solution-based indirect affinity selection mass spectrometry--a general tool for high-throughput screening of pharmaceutical compound libraries.

We show here that an automated solution-based affinity selection mass spectrometry (ASMS) system can be built exclusively from commercially available parts. The value of this technology lies in the throughput (~1 × 10(5) compounds/day) coupled with a low hit rate. The system, being a binding assay, requires little development time yielding a fast timeline between target availability and hit identification.

Inactivation of a class A and a class C β-lactamase by 6β-(hydroxymethyl)penicillanic acid sulfone.

β-Lactamase inhibitors (clavulanic acid, sulbactam, and tazobactam) contribute significantly to the longevity of the β-lactam antibiotics used to treat serious infections. In the quest to design more potent compounds and to understand the mechanism of action of known inhibitors, 6β-(hydroxymethyl)penicillanic acid sulfone (6β-HM-sulfone) was tested against isolates expressing the class A TEM-1 β-lactamase and a clinically important variant of the AmpC cephalosporinase of Pseudomonas aeruginosa, PDC-3. The addition of the 6β-HM-sulfone inhibitor to ampicillin was highly effective.

Sub-2 microm HPLC coupled with sub-ppm mass accuracy for analysis of pharmaceutical compound libraries.

Recent advances in accurate mass analysis are poised to allow the high-throughput production of accurate mass data on many more compounds than was previously available. It is shown that sub-ppm mass accuracy (producing elemental compositions) can be obtained on a simple TOF mass spectrometer operating in the manufacturer's standard mode. Concomitantly, there have been important technological advances in LC with respect to speed of analysis using sub-2 microm particle columns.

Automated sub-ppm mass accuracy on an ESI-TOF for use with drug discovery compound libraries.

An automated, routine method to obtain sub-ppm accurate mass data on a benchtop electrospray ionization time-of-flight (ESI-TOF) mass spectrometer is described. Standards in the mass range 114 to 734 Da were analyzed over a 5-day period to demonstrate intra- and interday precision and mean mass accuracy less than 1 ppm. One hundred drug discovery pharmaceutical compounds were used to demonstrate an absolute average mass accuracy of 0.

Method for determining the average degree of substitution of o-vanillin derivatized porcine somatotropin.

Electrospray mass spectral observation directly on a sample of a derivatized protein, such as porcine somatotropin (pST), affords a method for evaluating the degree of substitution of this protein. Derivatization of the lysine residues and the terminal amino residue here by formation of a Schiff base with a small aromatic aldehyde (in this case, o-vanillin) affords stabilization of the protein so that it may be used in a controlled release veterinary pharmaceutical formulation. This method permits direct observation of substitutions, optimization of manufacturing procedures for producing a commercial product, and permits quality evaluation of material.

LC-mass spectrometry analysis of N- and C-terminal boundary sequences of polypeptide fragments by limited proteolysis.

Limited proteolysis is an important and widely used method for analyzing the tertiary structure and determining the domain boundaries of proteins. Here we describe a novel method for determining the N- and C-terminal boundary amino acid sequences of products derived from limited proteolysis using semi-specific and/or non-specific enzymes, with mass spectrometry as the only analytical tool. The core of this method is founded on the recognition that cleavage of proteins with non-specific proteases is not random, but patterned.

An alternative mechanism of bioluminescence color determination in firefly luciferase.

Beetle luciferases (including those of the firefly) use the same luciferin substrate to naturally display light ranging in color from green (lambda(max) approximately 530 nm) to red (lambda(max) approximately 635 nm). In a recent communication, we reported (Branchini, B. R.

Yellow-green and red firefly bioluminescence from 5,5-dimethyloxyluciferin.

Beetle luciferases (including those of the firefly) use the same luciferin substrate to naturally display light ranging in color from green (lambda(max) similar 530 nm) to red (lambda(max) similar 635 nm). The original mechanism of bioluminescence color determination advanced by White and co-workers was based on the concept that the keto and enol tautomers of the emitter oxyluciferin produce red and green light, respectively. Alternatively, McCapra proposed that color variation is associated with conformations of the keto form of excited-state oxyluciferin.