A Simple Method for Quantification of Peptides and Proteins by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

Park, Kyung Man; Bae, Yong Jin; Ahn, Sung Hee; Kim, Myoung Soo

doi:10.1021/ac302807u

Cited by 33 publications

(61 citation statements)

References 32 publications

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“…We observed such direct proportionality over three orders of magnitude in analyte concentrations and proposed to use it as a calibration curve for analyte quantification [16]. 5.…”

Section: Ion Ratiomentioning

confidence: 82%

“…Subsequently, when the analyte was a peptide, we found that I(Analyte)/I(Matrix) was comparable to the analyte concentration in a solid sample [16]. The constancy of Q is an indication that an analyte ion may indeed be produced by the reaction in Equation 1 and that the reaction is nearly at equilibrium.…”

Section: Introductionmentioning

confidence: 91%

“…In our previous study of the MALDI of a peptide in a solid matrix [16], we measured the reaction quotient (Q, Equation 2) for the matrix-to-peptide proton transfer (Reaction 1) at a fixed value of T early . Initially, we approximated the neutral ratio, I([peptide])/I([matrix]), needed in the calculation of Q as the peptide concentration in the solid sample (later [34], we found that this approximation was valid because the depth profile of a peptide in CHCA prepared by vacuum-drying was nearly homogeneous).…”

Section: Mechanism For Analyte Ion Production and The Calibration Curvementioning

confidence: 99%

“…3. When T early was fixed, we found that the reaction quotient (Q) for the matrix-to-analyte proton transfer, reaction 1, was nearly constant [10,16].…”

Section: Introductionmentioning

confidence: 98%

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Investigations of Some Liquid Matrixes for Analyte Quantification by MALDI

Moon

Park

Ahn

et al. 2015

J. Am. Soc. Mass Spectrom.

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Abstract. Sample inhomogeneity is one of the obstacles preventing the generation of reproducible mass spectra by MALDI and to their use for the purpose of analyte quantification. As a potential solution to this problem, we investigated MALDI with some liquid matrixes prepared by nonstoichiometric mixing of acids and bases. Out of 27 combinations of acids and bases, liquid matrixes could be produced from seven. When the overall spectral features were considered, two liquid matrixes using α-cyano-4-hydroxycinnamic acid as the acid and 3-aminoquinoline and N,N-diethylaniline as bases were the best choices. In our previous study of MALDI with solid matrixes, we found that three requirements had to be met for the generation of reproducible spectra and for analyte quantification: (1) controlling the temperature by fixing the total ion count, (2) plotting the analyte-to-matrix ion ratio versus the analyte concentration as the calibration curve, and (3) keeping the matrix suppression below a critical value. We found that the same requirements had to be met in MALDI with liquid matrixes as well. In particular, although the liquid matrixes tested here were homogeneous, they failed to display spot-to-spot spectral reproducibility unless the first requirement above was met. We also found that analytederived ions could not be produced efficiently by MALDI with the above liquid matrixes unless the analyte was sufficiently basic. In this sense, MALDI processes with solid and liquid matrixes should be regarded as complementary techniques rather than as competing ones.

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“…We observed such direct proportionality over three orders of magnitude in analyte concentrations and proposed to use it as a calibration curve for analyte quantification [16]. 5.…”

Section: Ion Ratiomentioning

confidence: 82%

Section: Introductionmentioning

confidence: 91%

Section: Mechanism For Analyte Ion Production and The Calibration Curvementioning

confidence: 99%

“…3. When T early was fixed, we found that the reaction quotient (Q) for the matrix-to-analyte proton transfer, reaction 1, was nearly constant [10,16].…”

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Investigations of Some Liquid Matrixes for Analyte Quantification by MALDI

Moon

Park

Ahn

et al. 2015

J. Am. Soc. Mass Spectrom.

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“…In particular, Prof. Kim and coworkers have recently dedicated themselves towards the better understanding of the MALDI mechanism and the expansion of the MALDI analysis as a quantitative tool. [6][7][8][9] Another notable contribution made in his group was the coupling of UV light with MALDI technique as a photodissociation (PD) tool, [10][11][12] which has made an impact on the ensuing use of UV light in peptide sequencing mass spectrometry.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory (DFT) Study of Gas-phase O.C Bond Dissociation Energy of Models for o-TEMPO-Bz-C(O)-Peptide: A Model Study for Free Radical Initiated Peptide Sequencing

Kwon¹,

Kwon²,

Lee³

et al. 2014

Bulletin of the Korean Chemical Society

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The bond dissociation energy (BDE) of the chemical bond between the carbon and oxygen atoms of a simple TEMPO-derivative is calculated by employing the density functional theory, the 2 nd order Møller-Plesset (MP2) perturbation theory, and complete basis set (CBS) methods. We find that BDE of the positive ion of the TEMPO-derivative is larger at least by 7 kcal/mol than that of the negative ion, which implies that the dissociation reaction rate of the positive ion should be slower than that of the negative ion. Such theoretical predictions are contrary to the results of our previous experiments (Anal. Chem. 2013, 85, 7044), in which the larger energy was required for negative o-TEMPO-Bz-C(O)-peptides to undergo the dissociation reactions than for the positive ones. By comparing our theoretical results to those of the experiments, we conclude that the dissociation reaction of o-TEMPO-Bz-C(O)-peptide should occur in a complicated fashion with a charge, either positive or negative, probably being located on the amino acid residues of the peptide.

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Preparation of Homogeneous Solid Samples for Reproducible and Quantitative MALDI

Ahn

Park

Moon

et al. 2016

Bulletin Korean Chem Soc

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Preparing samples with good homogeneity is one of the requirements for generating reproducible matrix‐assisted laser desorption ionization (MALDI) spectra and for using them in analyte quantification. Thus far, we have not been successful in producing homogeneous solid samples from popular matrixes apart from α‐cyano‐4‐hydroxycinnamic acid (CHCA). In this work, we demonstrate the production of an outwardly homogeneous solid sample by loading a methanol solution of a matrix into a shallow reservoir on a coated MALDI sample plate and then vacuum‐drying it. Out of ten popular matrixes tested, seven yielded homogeneous samples. These were 9‐aminoacridine, 6‐aza‐2‐thiothymine, CHCA, 2,5‐dihydroxybenzoic acid, ferulic acid, sinapinic acid, and 2,4,6‐trihydroxyacetophenone. For MALDI with these matrixes, linear calibration curves covering wide dynamic ranges were acquired. Performances of these matrixes in various aspects of analyte quantification have been investigated.

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A Simple Method for Quantification of Peptides and Proteins by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

Cited by 33 publications

References 32 publications

Investigations of Some Liquid Matrixes for Analyte Quantification by MALDI

Investigations of Some Liquid Matrixes for Analyte Quantification by MALDI

Density Functional Theory (DFT) Study of Gas-phase O.C Bond Dissociation Energy of Models for o-TEMPO-Bz-C(O)-Peptide: A Model Study for Free Radical Initiated Peptide Sequencing

Preparation of Homogeneous Solid Samples for Reproducible and Quantitative MALDI

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