Interactome dynamics during heat stress signal transmission and reception.

Among evolved molecular mechanisms, cellular stress response to altered environmental conditions to promote survival is among the most fundamental. The presence of stress-induced unfolded or misfolded proteins and molecular registration of these events constitute early steps in cellular stress response. However, what stress-induced changes in protein conformations and protein-protein interactions within cells initiate stress response and how these features are recognized by cellular systems are questions that have remained difficult to answer, requiring new approaches.

A planar quadrupole device for transmitting and trapping ions in high vacuum.

Rationale: Hybrid mass spectrometers combine multiple mass analyzers to achieve optimal performance in terms of tandem mass spectrometry, high mass resolving power, and mass measurement accuracy for studying highly complex samples. As a result, the need for transport, trapping, and control of ion kinetic energies is critical for the successful integration of multiple mass analyzers and hybrid instrument operation. In addition, transportation of ion populations between two physically distinct locations can result in time-of-flight (TOF) discrimination against ions with widely disparate m/z values, compromising full mass spectral performance.

Application of frequency multiple FT-ICR-MS signal acquisition for improved proteome research.

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with liquid chromatography (LC) is a powerful combination useful in many research areas due to the utility of high mass resolving power and mass measurement accuracy for studying highly complex samples. Ideally, every analyte in a complex sample can be subjected to accurate mass MS/MS analysis to aid in identification. FT-ICR MS can provide high mass resolving power and mass accuracy at the cost of long data acquisition periods, reducing the number of spectra that can be acquired per unit time.

Applications and advancements of FT-ICR-MS for interactome studies.

The set of all intra- and intermolecular interactions, collectively known as the interactome, is currently an unmet challenge for any analytical method, but if measured, could provide unparalleled insight on molecular function in living systems. Developments and applications of chemical cross-linking and high-performance mass spectrometry technologies are beginning to reveal details on how proteins interact in cells and how protein conformations and interactions inside cells change with phenotype or during drug treatment or other perturbations. A major contributor to these advances is Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) technology and its implementation with accurate mass measurements on cross-linked peptide-pair precursor and fragment ions to enable improved identification methods.

Parallel Detection of Fundamental and Sixth Harmonic Signals Using an ICR Cell with Dipole and Sixth Harmonic Detectors.

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a powerful instrument for high-resolution analysis of biomolecules. However, relatively long signal acquisition periods are needed to achieve mass spectra with high resolution. The use of multiple detector electrodes for detection of harmonic frequencies has been introduced as one approach to increase scan rate for a given resolving power or to obtain increased resolving power for a given detection period.

Parallel detection in a single ICR cell: Spectral averaging and improved S/N without increased acquisition time.

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is well-renowned for its ultrahigh resolving power and mass measurement accuracy. As with other types of analytical instrumentation, achievable signal-to-noise ratio (S/N) is an important analytical figure of merit with FTICR-MS. S/N can be improved with higher magnetic fields and longer time-domain signal acquisition periods.

Characterization of Harmonic Signal Acquisition with Parallel Dipole and Multipole Detectors.

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a powerful instrument for the study of complex biological samples due to its high resolution and mass measurement accuracy. However, the relatively long signal acquisition periods needed to achieve high resolution can serve to limit applications of FTICR-MS. The use of multiple pairs of detector electrodes enables detection of harmonic frequencies present at integer multiples of the fundamental cyclotron frequency, and the obtained resolving power for a given acquisition period increases linearly with the order of harmonic signal.

Parallel Spectral Acquisition with Orthogonal ICR Cells.

FT-based high performance mass analyzers yield increased resolving power and mass measurement accuracy, yet require increased duration of signal acquisition that can limit many applications. The implementation of stronger magnetic fields, multiple detection electrodes for harmonic signal detection, and an array of multiple mass analyzers arranged along the magnetic field axis have been used to decrease required acquisition time. The results presented here show that multiple ion cyclotron resonance (ICR) mass analyzers can also be implemented orthogonal to the central magnetic field axis.

Parallel Spectral Acquisition with an Ion Cyclotron Resonance Cell Array.

Mass measurement accuracy is a critical analytical figure-of-merit in most areas of mass spectrometry application. However, the time required for acquisition of high-resolution, high mass accuracy data limits many applications and is an aspect under continual pressure for development. Current efforts target implementation of higher electrostatic and magnetic fields because ion oscillatory frequencies increase linearly with field strength.

Laser ablation sample transfer for mass spectrometry imaging.

Infrared laser ablation sample transfer (IR-LAST) is a novel ambient sampling technique for mass spectrometry. In this technique, a pulsed mid-IR laser is used to ablate materials that are collected for mass spectrometry analysis; the material can be a solid sample or deposited on a sample target. After collection, the sample can be further separated or analyzed directly by mass spectrometry.

Ambient laser ablation sampling for capillary electrophoresis mass spectrometry.

Rationale: Ambient laser ablation with mass spectrometric detection is a powerful method for direct analysis of biological samples in their native environment. Capillary electrophoresis (CE) can separate complex mixtures of biological molecules prior to mass spectrometry (MS) analysis and an ambient sampling interface for CE/MS will allow the detection of minor components.

Methods: An infrared (IR) laser ablated and transferred sample materials under ambient conditions for direct loading onto the CE separation column.

Infrared laser ablation sample transfer for on-line liquid chromatography electrospray ionization mass spectrometry.

We have demonstrated an on-line laser ablation sampling system and coupling of the system to liquid chromatography (LC) using an infrared (IR) laser to ablate and transfer materials into a flowing solvent stream. With this approach, samples are deposited on a microscope slide mounted on a translation stage and ablated in transmission geometry using a pulsed mid-IR laser. The ablated material is captured in an exposed flowing solvent stream that carries the ablated material to the electrospray source.

Infrared laser ablation sample transfer for MALDI imaging.

An infrared laser was used to ablate material from tissue sections under ambient conditions for direct collection on a matrix assisted laser desorption ionization (MALDI) target. A 10 μm thick tissue sample was placed on a microscope slide and was mounted tissue-side down between 70 and 450 μm from a second microscope slide. The two slides were mounted on a translation stage, and the tissue was scanned in two dimensions under a focused mid-infrared (IR) laser beam to transfer material to the target slide via ablation.

Infrared laser ablation sample transfer for MALDI and electrospray.

We have used an infrared laser to ablate materials under ambient conditions that were captured in solvent droplets. The droplets were either deposited on a MALDI target for off-line analysis by MALDI time-of-flight mass spectrometry or flow-injected into a nanoelectrospray source of an ion trap mass spectrometer. An infrared optical parametric oscillator (OPO) laser system at 2.

Detoxification of cytotoxic alachlor by glutathione: characterization of conjugated adducts by electrospray ionization tandem mass spectrometry.

The most commonly used chloroacetamide herbicide, alachlor, and its conjugated adducts have been characterized by electrospray ionization mass spectrometry (ESI-MS). The reactivity of glutathione toward alachlor has been evaluated by changing experimental parameters, such as pH, temperature, and tube lens offset voltage (TLOV) in aqueous methanol, and the products were subjected to collision-induced dissociation (CID) for further characterization. In the positive mode, CID proves the formation of cyclic species by elimination of glycine and NH(3) moiety, which is similar to protonated cysteine.