A preparative mass spectrometer to deposit intact large native protein complexes

Electrospray ion-beam deposition (ES-IBD) is a versatile tool to study the structure and reactivity of molecules from small metal clusters to large protein assemblies. It brings molecules gently into the gas phase, where they can be accurately manipulated and purified, followed by controlled deposition onto various substrates. In combination with imaging techniques, direct structural information on well-defined molecules can be obtained, which is essential to test and interpret results from indirect mass spectrometry techniques. To date, ion-beam deposition experiments are limited to a small number of custom instruments worldwide, and there are no commercial alternatives. Here we present a module that adds ion-beam deposition capabilities to a popular commercial MS platform (Thermo Scientific Q Exactive UHMR mass spectrometer). This combination significantly reduces the overhead associated with custom instruments, while benefiting from established high performance and reliability. We present current performance characteristics including beam intensity, landing-energy control, and deposition spot size for a broad range of molecules. In combination with atomic force microscopy (AFM) and transmission electron microscopy (TEM), we distinguish near-native from unfolded proteins and show retention of the native shape of protein assemblies after dehydration and deposition. Further, we use an enzymatic assay to quantify the activity of a noncovalent protein complex after deposition on a dry surface. Together, these results not only indicate a great potential of ES-IBD for applications in structural biology, but also outline the challenges that need to be solved for it to reach its full potential

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Electrochemical Characterization of Ca₆₅Mg₁₅Zn₂₀ Amorphous Alloy in Selected Physiological Fluids

The corrosion behavior of the bulk glassy samples of Ca₆₅Mg₁₅Zn₂₀ alloy was studied by electrochemical measurements and immersion tests in a simulated body fluid, physiological fluid, and the Ringer solution. The results of immersion show that the volume of H₂ evolved after 2 h in simulated body fluid (29.8 ml/cm²) is the highest in comparison with the results of measurements conducted in physiological fluid (11.3 ml/cm²) and the Ringer solution (7.4 ml/cm²). The electrochemical measurements indicated a shift of the corrosion potential (E_{corr}) from -1.58 V for plate tested in a physiological fluid to -1.56 V and -1.54 V for samples immersed in the Ringer solution and simulated body fluid, adequately. The X-ray diffraction measurements were used to determine composition of corrosion products. The corrosion products were mainly identified to be calcium carbonates and calcium/magnesium hydroxides

New One-Step Thiol Functionalization Procedure for Ni by Self-Assembled Monolayers

This article reports on a facile and fast strategy for the self-assembled monolayer (SAM) functionalization of nickel surfaces, employing cyclic voltammetry (CV) cycling of a suitable tailored solution containing the species to be adsorbed. Results are presented for ultrathin films formed on Ni by 1-hexadecanethiol (C16), l-cysteine (l-cys), and the poly­{methyl (2<i>R</i>)-3-(2,2′-bithiophen-4-ylsulfanyl)-2-[(tert-butoxycarbonyl)­amino]­propanoate} (PCT-L) thiophene-based chiral polymer. The effective formation of high-quality ultrathin organic films on the nickel was verified both electrochemically and by exploiting typical surface characterization techniques such as contact angle, ellipsometry, atomic force microscopy (AFM), polarization modulation–infrared reflection–absorption spectroscopy (PM–IRRAS), and X-ray photoelectron spectroscopy (XPS)