Matrix-assisted laser desorption/ionization mass spectrometric quantification of the mu opioid receptor agonist DAMGO in ovine plasma

Desiderio, Dominic M.; Wirth, Urs; Lovelace, Jerry L.; Fridland, Genevieve; Umstot, Edward S.; Nguyen, Thi M.‐D.; Schiller, Peter W.; Szeto, Hazel; Clapp, James F.

doi:10.1002/1096-9888(200006)35:6<725::aid-jms1>3.0.co;2-i

Cited by 33 publications

(8 citation statements)

References 40 publications

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“…In the cases examined, the two peptides were of similar molecular mass (1385.56 versus 1046.48 Da) but of different composition. Several studies reported the use of structural analogues (8,22), derivatives (8,10,11,19), functional analogues (9), molecules of similar hydrophobicity (12), or isotopically labeled derivatives (5,6,8,11) of the analyte as internal standards. Some of these have indeed published calibration lines with quite small mean relative standard deviations (6,12).…”

Section: Examining the Correlation Between The Relative Signal Intensmentioning

confidence: 85%

“…Lately MALDI-TOF MS has become a popular method for quantitative analysis of biomolecules (oligonucleotides, proteins, glycoproteins, etc.) originating from various sample types (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) or even for imaging tissue sections (13)(14)(15)(16)(17)(18)(23)(24)(25)(26). At the same time, several studies discuss the non-quantitative nature of MALDI-TOF MS (7, 8, 13, 19, 22, 26 -30).…”

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confidence: 85%

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Investigating the Quantitative Nature of MALDI-TOF MS

Szaéjli

Feheér

Medzihradszky

2008

Molecular & Cellular Proteomics

138

116

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MALDI-TOF MS has been applied by several groups to relative quantitative measurements. At the same time, the non-quantitative character of this method has been widely reported. We conducted experiments to test the reliability of this technique for quantitation using the statistical method of inverse confidence limit calculation for the first time in this context. The relationship between relative intensities of known amounts of standard peptides and their concentration ratios was investigated. We found that the concentration ratios determined by relative intensity measurements were highly inaccurate and strongly influenced by the molecular milieu of the sample analyzed. Thus, we emphasize the necessity of using the sample itself for calibration. We also performed experiments using an isotope-labeled derivative of the analyte as an internal standard for calibration line generation. As expected, the use of such standard led to a dramatic increase in precision and a less pronounced improvement in accuracy. We recommend performing a similar statistical analysis as a demonstration of reliability for every system where MALDI-TOF MS is used for quantitative measurements. Molecular & Cellular Proteomics 7: 2410 -2418, 2008.MALDI-TOF MS is a widely used analytical technique because of its excellent sensitivity, relatively high speed, and simplicity. As a consequence of producing mostly singly charged ions (1, 2) MALDI is especially suitable for mixture analysis. It is commonly used in proteomic studies (3) frequently without any prefractionation (4) as well as in the analysis of other biomolecules. Lately MALDI-TOF MS has become a popular method for quantitative analysis of biomolecules (oligonucleotides, proteins, glycoproteins, etc.) originating from various sample types (5-22) or even for imaging tissue sections (13)(14)(15)(16)(17)(18)(23)(24)(25)(26). At the same time, several studies discuss the non-quantitative nature of MALDI-TOF MS (7, 8, 13, 19, 22, 26 -30). The main problem of MALDI is its poor reproducibility (sample to sample and shot to shot), which makes most quantitative measurements quite difficult at best (19,27,31). This is especially true for complex samples. The presence of so-called hot spots or sweet spots is the main cause of the poor reproducibility and is therefore a factor strongly increasing measurement times and complicating automated measurements. Furthermore this phenomenon is one of the major factors hampering the use of MALDI MS for spatially resolved imaging (27). The reasons for sweet spot formation are not completely understood. It could be caused by variation in the amount and the crystallization of the matrix, the latter being a function of local analyte concentration. Dependence of signal intensities on the orientation of the matrix-analyte crystals relative to the spectrometer axis is also possible (27). The extent of hot spot formation depends strongly on the matrix used. For example, preparations with ␣-cyano-4-hydroxycinnamic acid (CHCA) 1 deliver relatively homogenous samples (...

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Section: Examining the Correlation Between The Relative Signal Intensmentioning

confidence: 85%

mentioning

confidence: 85%

Investigating the Quantitative Nature of MALDI-TOF MS

Szaéjli

Feheér

Medzihradszky

2008

Molecular & Cellular Proteomics

138

116

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“…More recently developed methods such as quantitative matrix-assisted laser-desorption/ ionization-mass spectrometric (MALDI-MS) approaches [46,47,48,49,50] or surface-enhanced laser desorption/ionization (SELDI) technologies [16,51,52] have been discussed in the literature. In general, most of the immunological methods are characterized by low limits of detection (pico-to femtomolar concentrations), high sample throughput, high sensitivity and selectivity.…”

Section: Methods For Peptide Quantificationmentioning

confidence: 99%

Analytical procedures for quantification of peptides in pharmaceutical research by liquid chromatography?mass spectrometry

John¹,

Walden²,

Schäfer³

et al. 2004

Analytical and Bioanalytical Chemistry

155

104

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Peptide quantification by liquid chromatography-mass spectrometry (LC-MS) combines the high resolving power of reversed-phase (RP) chromatography with the excellent selectivity and sensitivity of mass spectrometric detection. On the basis of comprehensive practical experience in the analysis of small molecules, pharmaceutical research is developing technologies for analysis of a growing number of peptidic drug candidates. This article is a detailed review of procedures based on LC-MS techniques for quantitative determination of peptides. With the focus on pharmaceutical applications several technologies for sample preparation, various aspects of peptide chromatography, important characteristics of ESI-MS, selectivity of MS-detection modes, the large variability of internal standards, and modern instrumentation are discussed. The demand for reliable, robust, sensitive, and accurate methods is discussed using numerous examples from the literature, complemented by experiments and results from our laboratory.

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“…Compared with other available techniques, this method affords advantages in specificity and sensitivity for angiotensin peptide detection (37,38). After chronic Ang II infusion, we find that renal Ang II levels are more than 5-fold higher in ACE2-deficient mice than in controls, indicating that the more severe hypertension in ACE2-deficient mice is due to impaired metabolism of Ang II in the kidney.…”

Section: Figurementioning

confidence: 99%

Altered blood pressure responses and normal cardiac phenotype in ACE2-null mice

et al. 2006

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The carboxypeptidase ACE2 is a homologue of angiotensin-converting enzyme (ACE). To clarify the physiological roles of ACE2, we generated mice with targeted disruption of the Ace2 gene. ACE2-deficient mice were viable, fertile, and lacked any gross structural abnormalities. We found normal cardiac dimensions and function in ACE2-deficient animals with mixed or inbred genetic backgrounds. On the C57BL/6 background, ACE2 deficiency was associated with a modest increase in blood pressure, whereas the absence of ACE2 had no effect on baseline blood pressures in 129/SvEv mice. After acute Ang II infusion, plasma concentrations of Ang II increased almost 3-fold higher in ACE2-deficient mice than in controls. In a model of Ang II-dependent hypertension, blood pressures were substantially higher in the ACE2-deficient mice than in WT. Severe hypertension in ACE2-deficient mice was associated with exaggerated accumulation of Ang II in the kidney, as determined by MALDI-TOF mass spectrometry. Although the absence of functional ACE2 causes enhanced susceptibility to Ang II-induced hypertension, we found no evidence for a role of ACE2 in the regulation of cardiac structure or function. Our data suggest that ACE2 is a functional component of the renin-angiotensin system, metabolizing Ang II and thereby contributing to regulation of blood pressure.

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Matrix-assisted laser desorption/ionization mass spectrometric quantification of the mu opioid receptor agonist DAMGO in ovine plasma

Cited by 33 publications

References 40 publications

Investigating the Quantitative Nature of MALDI-TOF MS

Investigating the Quantitative Nature of MALDI-TOF MS

Analytical procedures for quantification of peptides in pharmaceutical research by liquid chromatography?mass spectrometry

Altered blood pressure responses and normal cardiac phenotype in ACE2-null mice

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