Improved Resolution and Very High Sensitivity in MALDI TOF of Matrix Surfaces Made by Fast Evaporation

Vorm, Ole; Roepstorff, Peter; Mann, Matthias

doi:10.1021/ac00091a044

Cited by 683 publications

(525 citation statements)

References 14 publications

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“…Our experiment showed that the other two polyphenols (ECG and EGCG) possess greater antioxidant activity over GA both in the free and encapsulated state. A similar effect was observed in the DPPH assay ( Figure 12) indicating that the polyphenols with a greater number of hydroxyl groups can effectively scavenge the DPPH_ radical which is also evident from the lower EC 50 (amount of antioxidant needed to decrease the radical concentration by 50%) of ECG (4.2 6 0.1) and EGCG (3.6 6 0.0) as compared to GA (5.1 6 0.1). [80] Although the percentage inhibition values of the polyphenols are close to one another, the tread in antioxidant activity obtained from the DPPH assay is consistent with the result obtained from the DT fluorescence study.…”

Section: Docking Studiessupporting

confidence: 67%

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β‐cyclodextrin encapsulated polyphenols as effective antioxidants

et al. 2017

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Formation of dityrosine (DT) cross-linkages in proteins is one of the most widely used markers of oxidative stress. Ribonuclease A (RNase A) has 6 Tyr residues and shows a characteristic DT fluorescence peak upon oxidation in addition to major changes in its secondary structure. DT formation can be prevented by using polyphenols (GA, ECG, and EGCG) which are known to have strong antioxidant activity. However, it has been observed that ECG and EGCG initiate protein oligomerization due to protein-polyphenol cross-linkages. To prevent the formation of such crosslinkages we have used b-cyclodextrin (b-CD) to encapsulate the polyphenols and studied its antioxidant properties along with that of free polyphenols. The polyphenol/b-cyclodextrin (b-CD) inclusion complexes not only prevent DT formation but also reduce protein oligomerization. This may be attributed to the fact that the quinone forming rings of ECG and EGCG become encapsulated in the cavity of b-CD and are no longer available for protein cross-linking.b-cyclodextrin encapsulation, dityrosine, oxidative stress, polyphenols, protein oligomerization | I N TR ODU C TI ONBiological aging in mammalian cells is a direct indication of oxidative stress in proteins. [1] These oxidatively modified forms of proteins are generated due to the presence of reactive oxygen species (ROS) such as hydroxyl and superoxide free radicals. [2,3] Persulfates, a key ingredient in flour, are a source of sulfate (SO 2 4 ) free radicals under neutral pH. [4,5] Due to the higher oxidizing power of the sulfate radical (E 0 5 12.60 V) and longer half-life period over the OH radical, it has drawn attention in recent times as a powerful oxidizing agent. [6][7][8] Many chemical and cosmetic industries require persulfates as their key components [9] and workers often suffer from skin and respiratory diseases due to hypersensitive reactions. [10] Generally, the lower thermal energy at room temperature (25-508C) is not sufficient enough to activate persulfate, but generation of SO 2 4 radical is facilitated in presence of metal cations. Since proteins tend to lose their structure and function at high temperatures, [11] we have carried out the oxidation of ribonuclease A (RNase A) in presence of persulfate using cobalt (II) ion at 378C. [12] Cobalt is an integral component of vitamin B12 and thus physiologically found in most tissues mainly in liver and kidney. [13,14] Gill et al., reported the formation of oligomeric species (dimer, trimer, tetramer) when RNase A was exposed to KHSO 5 in presence of metal ions such as Ni 21 and Cu 21 and the high molecular weight species were identified using SDS-PAGE. [12] An important biomarker of oxidative stress is the dityrosine moiety generated due to the covalent linkage of two Tyr residues. [15] Dityrosine bond formation is an indication of aging, and disease related problems since it generally occurs during amyloid fibril formation, [16] Parkinson disease, [17] cerebrospinal fluid damage, [18] and also in the cataract of the eye lens. [19,20] D...

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Section: Docking Studiessupporting

confidence: 67%

“…In order of ensure the formation of RNase A dimer or higher oligomeric species, MALDI-TOF analysis [50] was performed. The matrix was pre- …”

Section: Matrix-assisted Laser Desorption Ionization-time Of Flightmentioning

confidence: 99%

β‐cyclodextrin encapsulated polyphenols as effective antioxidants

et al. 2017

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“…Plasmids, recombinant protein expression, and purification excised and in-gel digested with trypsin + Three tenths of a microliter of the total digest solution was analyzed by peptide mass mapping on a Bruker REFLEX MALDI time-of-flight mass spectrometer (Bruker-Franzen, Bremen, Germany) using the fast evaporation technique for matrix preparation (Vorm et al+, 1994)+ A nonredundant protein database containing more than 300,000 entries was searched with the peptide masses+ In cases when the identification was not certain, the peptide mixture was extracted, desalted on a 100-nL Poros R2 column, eluted directly into a nano electrospray needle, and analyzed on a triple quadrupole tandem mass spectrometer (API III, PE-Sciex, Ontario, Canada; Wilm et al+, 1996)+ Proteins were identified using the sequence tag algorithm and the PeptideSearch program (Mann & Wilm, 1994)+ Tandem MS experiments were carried on a triple quadrupole mass spectrometer (API III, PE-Sciex)+…”

Section: Methodsmentioning

confidence: 99%

The C-terminal domain of TAP interacts with the nuclear pore complex and promotes export of specific CTE-bearing RNA substrates

Bachi

Braun

Rodrigues

et al. 2000

RNA

305

384

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“…There are various types of sample preparation methods for MALDI-TOF-MS analysis, such as the drieddroplet [1], fast evaporation [33], vacuum drying [34], sandwich [35], and two-layer [36] methods. Among these techniques, the dried-droplet method is one of the most frequently used for MALDI-TOF-MS analysis in the case of solution (analyte) to solution (matrix) conditions.…”

Section: Optimizing Sample Preparation Methodsmentioning

confidence: 99%

MALDI-TOF-MS analysis of small molecules using modified mesoporous material SBA-15 as assisted matrix

Kim

et al. 2009

J. Am. Soc. Mass Spectrom.

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Mesoporous silica, SBA-15 was successfully functionalized with quinoline moiety, and was applied as a matrix in the MALDI-TOF-MS analysis of small molecules. The modified SBA-15 material propoxy) quinoline, SBA-15-8QSi] was obtained by using calcined SBA-15 and 8-hydroxy quinoline. The structure of the functionalized mesoporous material was systemically characterized by TEM, the N 2 adsorption-desorption isotherm technique and FT-IR spectra. Compared with DHB and SBA-15, SBA-15-8QSi demonstrated several advantages in the analysis of small molecules with MALDI-TOF-MS, such as less background interference ions, high homogeneity, and better reproducibility. Based on these results, the various analytical parameters were optimized. The ideal operating conditions were (1) methanol used as the dissolving solvent; (2) sample first dropping method; (3) a ratio between the analyte and the matrix of 3.5:10. Under these optimization conditions, a low detection limit (8 pmol for L-Arginine-HCl) and high reproducibility (Յ29%) were obtained. This technique was successfully applied to the analysis of various types of small molecules, such as saccharides, amino acids, metabolites, and natural honey. [7], and synthetic polymers [8,9]. However, the application of MALDI-TOF-MS in small molecules analysis has been limited, mainly due to ion interference originating from matrices in the low molecule weight region (Ͻ500 Da) [10,11]. To overcome this problem, several alternative matrices, such as high mass molecules [12,13] There has been a great deal of interest in ordered mesoporous materials due to their regular pore sizes in the mesoporous range, high surface areas, high pore volumes, and easy functionalization since they were first reported in 1992 [23,24]. Recently, there have been significant advances in the preparation and modification of mesoporous materials, which allows their utilization in various applications, such as adsorbents [25], catalyst supports [26], nano-templates [27], and nanomaterials [28] for advanced electronics. In general, the pore surfaces of mesoporous silica materials are covered with a layer of silanol groups (Si-OH), which can act as the binding sites for desired functional groups via covalent grafting on the surfaces. Hu et al. reported on titanium (IV) immobilized mesoporous silica particles which were used as an enriching trap for small molecules (phosphorylated peptides), determined with MALDI-TOF-MS [29]. In addition, mesoporous silica materials have the advantage of optical transparency in the visible region [30].Herein, we successfully functionalized the mesoporous silica, SBA-15 with an 8-hydroxy quinoline group (SBA-15-8QSi hereafter), and applied the functional material as a matrix for MALDI-TOF-MS analysis. The SBA-15-8QSi material exhibited less ion backAddress reprint requests to Dr.

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Improved Resolution and Very High Sensitivity in MALDI TOF of Matrix Surfaces Made by Fast Evaporation

Abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF) is becoming a standard tool in mass spectrometry in general and protein analysis in particular.

Cited by 683 publications

References 14 publications

β‐cyclodextrin encapsulated polyphenols as effective antioxidants

β‐cyclodextrin encapsulated polyphenols as effective antioxidants

The C-terminal domain of TAP interacts with the nuclear pore complex and promotes export of specific CTE-bearing RNA substrates

MALDI-TOF-MS analysis of small molecules using modified mesoporous material SBA-15 as assisted matrix

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