Localization of noncovalent complexes in MALDI-preparations by CLSM

Horneffer, Verena; Strupat, Kerstin; Hillenkamp, Franz

doi:10.1016/j.jasms.2006.06.028

Cited by 30 publications

(30 citation statements)

References 32 publications

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“…To investigate the MALDI process, many studies have focused on sample morphology using different imaging experiments. Sample heterogeneity and distribution of molecules within the MALDI solid sample have been explored using microscopy techniques, such as optical microscopy [6,7], scanning electron microscopy [8 -12], atomic force microscopy [12], and confocal laser scanning microscopy [13,14]. Spectroscopic techniques, such as fluorescence spectrophotometry [13] or Raman spectrometry [8] were also implemented in conjunction with microscopy to obtain complementary information.…”

mentioning

confidence: 99%

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Pizzala

Barrère

Mazarin

et al. 2009

J. Am. Soc. Mass Spectrom.

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Solid-state Nuclear magnetic resonance (NMR) was used here to explore structural characteristics of samples to be subjected to matrix-assisted laser desorption/ionization (MALDI) and prepared without the use of any solvent. The analytical systems scrutinized in NMR were mixtures of a 2,5-dihydroxybenzoic acid (2,5-DHB) matrix and caesium fluoride (CsF), used as the cationization agent in synthetic polymer MALDI mass analysis, at different molar ratios (1:1, 5:1, and 10:1). Complementary information could be obtained from 13 C, 133 Cs, and 19 F NMR spectra. Grinding the matrix together with the salt in the solid state was shown to induce a strong modification in the molecular organization within the MALDI sample. The evidenced mechano-induced reactions allow strong interactions between the matrix and the cation, up to the formation of a salt, and only occur in the presence of some water molecules. Addition of a poly(ethylene oxide) polymer as the analyte did not further modify the observed molecular organizations. Although relative matrix and salt concentrations in the scrutinized samples were unusual for MALDI analysis, mass spectra of good quality could be obtained and revealed that cation attachment on polymers during the MALDI process is not a matrix-independent event since a lower ionization efficiency was obtained from highly organized solid samples, mostly consisting of 2,5-DHB caesium salt species. (J Am Soc Mass Spectrom 2009, 20, 1906 -1911) © 2009 American Society for Mass Spectrometry M atrix-assisted laser desorption/ionization (MALDI) is widely used as an efficient ionization method to characterize synthetic polymers by time-of-flight mass spectrometry (TOF MS) [1,2]. A key point in the success of a MALDI-MS analysis is sample preparation, that is, proper matrix and cation selection as well as solid-state organization. The matrix actually plays multiple roles in the MALDI process and should accordingly present specific properties. Some criteria are clearly defined, such as a strong absorptivity at the employed laser wavelength or good vacuum stability, while other requirements, such as a good miscibility of the matrix with the analyte in the solid state, are not easily related to physico-chemical parameters of the matrix. As a result, prediction for the optimal matrix-polymer system is still not possible and sample preparation methods are usually developed from published protocols that were shown to work for a given polymeric system [3]. In particular, solvent-free MALDI was recently proposed as an alternative to the conventional dried droplet method [4,5].Despite MALDI being a widely used technique, mechanisms underlying this desorption/ionization process are still not fully understood. To investigate the MALDI process, many studies have focused on sample morphology using different imaging experiments. Sample heterogeneity and distribution of molecules within the MALDI solid sample have been explored using microscopy techniques, such as optical microscopy [6,7], scanning electron microscopy [8 -...

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mentioning

confidence: 99%

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Pizzala

Barrère

Mazarin

et al. 2009

J. Am. Soc. Mass Spectrom.

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“…In several cases, the peak for the intact and specific complex is only observed for the first few laser shots onto a fresh sample spot, and the subsequent irradiation of the same position produces dissociated subunits [43][44][45]. However, that is not the case in this study-the number of laser shots has little impact on the intensity ratios of the complexes to calmodulin.…”

Section: Detection Of the Intact Calmodulin-peptide Complexes Using Dmentioning

confidence: 65%

“…The formation of noncovalent complexes between calmodulin and its target peptides (melittin and substance P) was examined using direct MALDI-MS as the first step because most of the previous studies on noncovalent interactions focused on the direct detection of the intact complexes [24,[42][43][44][45]. To check the specificity of the assay, the peptide bradykinin with no affinity for calmodulin was added as a nonbinding control (1:1 M ratio).…”

Section: Detection Of the Intact Calmodulin-peptide Complexes Using Dmentioning

confidence: 99%

“…Previous studies have revealed that some instrumental parameters may influence the observation of the specific noncovalent complexes [42][43][44][45]. In several cases, the peak for the intact and specific complex is only observed for the first few laser shots onto a fresh sample spot, and the subsequent irradiation of the same position produces dissociated subunits [43][44][45].…”

Section: Detection Of the Intact Calmodulin-peptide Complexes Using Dmentioning

confidence: 99%

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Investigation of calmodulin-peptide interactions using matrix-assisted laser desorption/ionization mass spectrometry

Wang

Cui

et al. 2008

J. Am. Soc. Mass Spectrom.

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In this report, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used to study the binding interactions between calmodulin and two target peptides (melittin and substance P). Various matrix conditions were tested and the less acidic matrix DHAP and THAP were found to favor the survival of the intact calcium-calmodulin as well as the calmodulin-peptide complexes. However, the application of direct MALDI-MS to detect the intact complexes turned out to be very difficult due to the dissociation of the complexes and the formation of nonspecific aggregates. In contrast, the specific binding of the target peptides to calmodulin could be easily deduced using intensity-fading (IF) MALDI-MS. Compared with the nonbinding control, clear reduction in the ion abundances of the target peptides was observed with the addition of calmodulin. Relative binding affinities of different peptides towards the protein could also be estimated using IF-MALDI-MS. This study may extend the application of IF-MALDI-MS in the analysis of noncovalent complexes and offer a perspective into the utility of MALDI-MS as an alternative approach to study the peptides binding to calmodulin.

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“…[38] In this study, we investigated whether this first-shot phenomenon may also be characteristic of supramolecular chemical assemblies. Figure 3 shows the spectra of the supramolecular grid [(L 4 ) 4 Co 4 ] that were obtained with the layered sample preparation method and with THAP as the matrix (see Exp.…”

Section: Maldi Laser Shot Optimizationmentioning

confidence: 99%

A Novel MALDI‐MS Approach for the Analysis of Neutral Metallosupramolecular Architectures

et al. 2011

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Matrix assisted laser desorption/ionisation mass spectrometry (MALDI-MS) methods have been developed for the characterisation of neutral [2ϫ2] metallogrids derived from diimine, dihydrazone and diacylhydrazone ligands. Such grids may be protonated in solution to give cationic species but in most cases these are labile, so that rather delicate conditions are required for observation of the intact metallogrids as monoprotonated derivatives in the gas phase. As a MALDI matrix, 2,4,6-trihydroxyacetophenone (THAP) is sufficiently acidic to enable monoprotonation of the grids unaccompanied by dissociation, and if the grid sample is initially deposited by a layering technique to avoid any preliminary dissociation in solution the mass spectrum of the intact mono-

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Localization of noncovalent complexes in MALDI-preparations by CLSM

Cited by 30 publications

References 32 publications

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Investigation of calmodulin-peptide interactions using matrix-assisted laser desorption/ionization mass spectrometry

A Novel MALDI‐MS Approach for the Analysis of Neutral Metallosupramolecular Architectures

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