A Mass Spectrometry Investigation of the Conformational Changes in Adrenocorticotropic Hormones

2002 ◽  
Vol 8 (5) ◽  
pp. 381-387 ◽  
Author(s):  
Hui Lin ◽  
Chhabil Dass
Keyword(s):  
Mass Spectrometry ◽  
Conformational Changes ◽  
Aqueous Media ◽  
Charge State Distribution ◽  
Random Coil ◽  
Helical Conformation ◽  
Ionization Mass ◽  
Time Resolved ◽  
Esi Ms ◽  
Α Helix

Electrospray ionization-mass spectrometry (ESI-MS) was employed to study methanol-induced conformational changes in adrenocorticotrophic hormone (ACTH). ACTH, a 39–residue peptide, is a member of the proopiomelanocortin family of peptides. Charge-state distribution (CSD) and hydrogen–deuterium (H/D) exchange were used to monitor the conformational changes as a function of methanol concentration. The latter experiments were conducted via time-resolved ESI-MS in a continuous-flow apparatus. The CSD and the H/D exchange experimental data both reveal that ACTH exists, presumably in a random coil open structure in aqueous media, but assumes a more compact helical conformation with increased concentration of methanol. The H/D exchange experiments also reveal that 79% of ACTH is present as α-helix in mixed water-methanol solvent media.

2003 Fred Beamish Award Lecture — Exploring the dynamics of biological systems by mass spectrometry

2004 ◽  
Vol 82 (11) ◽  
pp. 1565-1580 ◽  
Author(s):  
Lars Konermann
Keyword(s):  
Mass Spectrometry ◽  
Protein Interactions ◽  
High Throughput Screening ◽  
Structural Changes ◽  
Structural Information ◽  
Ionization Mass ◽  
Time Resolved ◽  
Rapid Mixing ◽  
Esi Ms ◽  
Compound Libraries

This review describes the use of electrospray ionization mass spectrometry (ESI-MS) in conjunction with on-line rapid mixing techniques. This combination, termed "time-resolved" ESI-MS, provides a powerful approach for studying solution-phase reactions on timescales as short as a few milliseconds. Of particular interest is the application of this technique for monitoring protein folding reactions. Time-resolved ESI-MS can provide detailed information on structural changes of the polypeptide chain, while at the same time probing the occurrence of noncovalent ligand–protein interactions. Especially when used in combination with hydrogen–deuterium pulse labeling, these measurements yield valuable structural information on short-lived folding intermediates. Similar approaches can be used to monitor the dynamics of proteins under equilibrium conditions. Another important application of time-resolved ESI-MS are mechanistic studies on enzyme-catalyzed processes. These reactions can be monitored under presteady-state conditions, without requiring artificial chromophoric substrates or radioactive labeling. We also discuss the use of ESI-MS for monitoring noncovalent ligand–protein interactions by diffusion measurements. In contrast to conventional MS-based techniques, this approach does not rely on the preservation of noncovalent interactions in the gas phase. It appears that diffusion measurements by ESI-MS could become an interesting alternative to existing methods for the high throughput screening of compound libraries in the context of drug discovery.Key words: reaction intermediate, rapid mixing, kinetics, protein conformation, protein function.

Characterization of the conformational changes in recombinant human metallothioneins using ESI-MS and molecular modeling

2007 ◽  
Vol 85 (10) ◽  
pp. 898-912 ◽  
Author(s):  
Jayna Chan ◽  
Zuyun Huang ◽  
Ian Watt ◽  
Peter Kille ◽  
Martin J Stillman
Keyword(s):  
Mass Spectrometry ◽  
Molecular Modeling ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Low Ph ◽  
Random Coil ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Molecular Models ◽  
Esi Ms

Electrospray ionization mass spectrometry (ESI-MS) data and molecular modeling calculations were used to gain mechanistic, conformational, and domain-specific information from the acid-induced demetallation reactions of human metallothionein. The recombinant proteins studied were the single α- and β-rhMT-1a domains and the βα- and αβ-rhMT-1a two-domain species, based on the human metallothionein 1a sequence. Complete molecular models (MM3/MD) for all the fully metallated and demetallated species using a modified force field are reported for the first time. Basic residues that contribute to the ESI-MS charge states are identified from the molecular models. Demetallation took place under equilibrium conditions within a narrow pH range. For the two-domain proteins, these results support a demetallation mechanism involving the initial complete demetallation of one domain followed by the other for both βα-rhMT and αβ-rhMT. Based on the stability of the separate domains, the β domain is predicted to demetallate first in the two-domain rhMTs. Both the α domain and the β domain were observed to bind an excess of one Cd2+ ion. The metallated rhMT structures were shown to have very stable conformations, but only when fully metallated. Two or more conformations were observed at low pH in the ESI-MS data, which are interpreted as arising from the presence of structure, as opposed to a random coil, in the apo-rhMT. This is the first report of the existence of a structure in the two-domain metal-free apo-MT proteins. Only at extremely low pH does the structure open fully to give the highest charge distribution, which is associated with a random coil. Pre-existing structural features in the apo-MT would explain why the metallation reactions occur so rapidly.Key words: recombinant human metallothionein-1 (rhMT1), electrospray ionization mass spectrometry (ESI-MS), circular dichroism (CD), molecular mechanics/molecular dynamics (MM3/MD).

scholarly journals Synthesis, Biomacromolecular Interactions, Photodynamic NO Releasing and Cellular Imaging of Two [RuCl(qn)(Lbpy)(NO)]X Complexes

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2545
Author(s):  
Luna Song ◽  
Hehe Bai ◽  
Chenyang Liu ◽  
Wenjun Gong ◽  
Ai Wang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Confocal Imaging ◽  
Epr Spectra ◽  
Distorted Octahedral Geometry ◽  
Ionization Mass ◽  
Time Resolved ◽  
Pbr322 Dna ◽  
Vis Spectroscopy ◽  
No Release ◽  
Ft Ir

Two light-activated NO donors [RuCl(qn)(Lbpy)(NO)]X with 8-hydroxyquinoline (qn) and 2,2′-bipyridine derivatives (Lbpy) as co-ligands were synthesized (Lbpy1 = 4,4′-dicarboxyl-2,2′-dipyridine, X = Cl− and Lbpy2 = 4,4′-dimethoxycarbonyl-2,2′-dipyridine, X = NO3−), and characterized using ultraviolet–visible (UV-vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (1H NMR), elemental analysis and electrospray ionization mass spectrometry (ESI-MS) spectra. The [RuCl(qn)(Lbpy2)(NO)]NO3 complex was crystallized and exhibited distorted octahedral geometry, in which the Ru–N(O) bond length was 1.752(6) Å and the Ru–N–O angle was 177.6(6)°. Time-resolved FT-IR and electron paramagnetic resonance (EPR) spectra were used to confirm the photoactivated NO release of the complexes. The binding constant (Kb) of two complexes with human serum albumin (HSA) and DNA were quantitatively evaluated using fluorescence spectroscopy, Ru-Lbpy1 (Kb~106 with HSA and ~104 with DNA) had higher affinity than Ru-Lbpy2. The interactions between the complexes and HSA were investigated using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) and EPR spectra. HSA can be used as a carrier to facilitate the release of NO from the complexes upon photoirradiation. The confocal imaging of photo-induced NO release in living cells was successfully observed with a fluorescent NO probe. Moreover, the photocleavage of pBR322 DNA for the complexes and the effect of different Lbpy substituted groups in the complexes on their reactivity were analyzed.

scholarly journals Correction: Taliaferro, L. et al. Evaluation of the Broad-Range PCR-Electrospray Ionization Mass Spectrometry (PCR/ESI-MS) System and Virus Microarrays for Virus Detection. Viruses 2014, 6, 1876-1896

Viruses ◽  
2014 ◽  
Vol 6 (11) ◽  
pp. 4664-4665
Author(s):  
Lanyn Taliaferro ◽  
Teresa Galvin ◽  
Hailun Ma ◽  
Syed Shaheduzzaman ◽  
Dhanya Williams ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Virus Detection ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Esi Ms

Surface Reaction Kinetics of CH3in CH4RF Discharge Studied by Time-Resolved Threshold Ionization Mass Spectrometry

1997 ◽  
Vol 36 (Part 1, No. 7B) ◽  
pp. 4752-4755 ◽  
Author(s):  
Masaharu Shiratani ◽  
Jacques Jolly ◽  
Hervé Videlot ◽  
Jérôme Perrin
Keyword(s):  
Mass Spectrometry ◽  
Reaction Kinetics ◽  
Surface Reaction ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Time Resolved ◽  
Threshold Ionization ◽  
Surface Reaction Kinetics ◽  
Kinetics Of

scholarly journals Analysis of Inositol Phosphate Metabolism by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry (CE-ESI-MS)

2020 ◽  
Author(s):  
Danye Qiu ◽  
Miranda S. Wilson ◽  
Verena B. Eisenbeis ◽  
Robert K. Harmel ◽  
Esther Riemer ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Capillary Electrophoresis ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Inositol Phosphate ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Phosphate Metabolism ◽  
Esi Ms ◽  
Inositol Phosphate Metabolism

AbstractThe analysis of myo-inositol phosphates (InsPs) and myo-inositol pyrophosphates (PP-InsPs) is a daunting challenge due to the large number of possible isomers, the absence of a chromophore, the high charge density, the low abundance, and the instability of the esters and anhydrides. Given their importance in biology, an analytical approach to follow and understand this complex signaling hub is highly desirable. Here, capillary electrophoresis (CE) coupled to electrospray ionization mass spectrometry (ESI-MS) is implemented to analyze complex mixtures of InsPs and PP-InsPs with high sensitivity. Stable isotope labeled (SIL) internal standards allow for matrix-independent quantitative assignment. The method is validated in wild-type and knockout mammalian cell lines and in model organisms. SIL-CE-ESI-MS enables for the first time the accurate monitoring of InsPs and PP-InsPs arising from compartmentalized cellular synthesis pathways, by feeding cells with either [13C6]-myo-inositol or [13C6]-D-glucose. In doing so, we uncover that there must be unknown inositol synthesis pathways in mammals, highlighting the unique potential of this method to dissect inositol phosphate metabolism and signalling.

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