Capillary liquid chromatography/mass spectrometry

Tomer, Kenneth B.; Moseley, M. Arthur; Deterding, Leesa J.; Parker, Carol E.

doi:10.1002/mas.1280130504

Cited by 73 publications

(35 citation statements)

References 110 publications

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“…The ESI analysis of the HPLC-purified subtilisin fragment was performed by using a Micromass Platform II (Altrincham, UK) single quadrupole mass spectrometer. The sample was infused into the mass spectrometer at 5 ml/min using a pressure injection vessel (26). A Micromass Q-Tof (Altrincham, UK) hybrid mass spectrometer, equipped with a quadrupole mass filter and an orthogonal acceleration time-of-flight mass spectrometer, was used for the analysis of the tryptic peptide mixture of the catalytic fragment after trypsinolysis.…”

Section: Methodsmentioning

confidence: 99%

The Tetratricopeptide Repeat Domain and a C-terminal Region Control the Activity of Ser/Thr Protein Phosphatase 5

Sinclair¹,

Borchers²,

Parker³

et al. 1999

Journal of Biological Chemistry

111

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Protein Ser/Thr phosphatase 5 is a 58-kDa protein containing a catalytic domain structurally related to the catalytic subunits of protein phosphatases 1, 2A, and 2B and an extended N-terminal domain with three tetratricopeptide repeats. The activity of this enzyme is stimulated 4 -14-fold in vitro by polyunsaturated fatty acids and anionic phospholipids. The structural basis for lipid activation of protein phosphatase 5 was examined by limited proteolysis and site-directed mutagenesis. Trypsinolysis removed the tetratricopeptide repeat domain and increased activity to approximately half that of lipid-stimulated, full-length enzyme. Subtilisin removed the tetratricopeptide repeat domain and 10 residues from the C terminus, creating a catalytic fragment with activity that was equal to or greater than that of lipid-stimulated, full-length enzyme. Catalytic fragments generated by proteolysis were no longer stimulated by lipid, and degradation of the tetratricopeptide repeat domain was decreased by association with lipid. A truncated mutant missing 13 C-terminal residues was also insensitive to lipid and was as active as full-length, lipid-stimulated enzyme. These results suggest that the C-terminal and N-terminal domain act in a coordinated manner to suppress the activity of protein phosphatase 5 and mediate its activation by lipid. These regions may be targets for the regulation of protein phosphatase 5 activity in vivo.Protein Ser/Thr phosphatases, together with protein Ser/Thr kinases, play an essential role in regulating a variety of cellular processes. The major structural family of protein Ser/Thr phosphatases, the PPP 1 family, includes PP1, PP2A, and 2B, also known as calcineurin, as well as several newer family members about which little is known (1). A growing body of evidence indicates that PPP family members are subject to complex regulation. For example, the catalytic subunits of PP1 and PP2A are bound to regulatory subunits and docking proteins that control their activity, substrate specificity, and subcellular localization (2, 3). In addition to activation by calcium and calmodulin, calcineurin is also associated with proteins that control its intracellular location and activity (4, 5).Protein phosphatase 5 (PP5) is a member of the PPP family with a C-terminal catalytic domain related to those of PP1, PP2A, and calcineurin, and an N-terminal domain consisting of three tetratricopeptide repeats or TPRs (6 -8). Tetratricopeptide repeats occur in a variety of unrelated proteins and are thought to mediate protein-protein interactions (9 -11). The TPR domain of PP5 interacts with a number of proteins in vitro, including the atrial natriuretic peptide receptor (7), Cdc 16p and Cdc 27p, which are two TPR-containing subunits of the anaphase-promoting complex (12), and hCRY2, a human homologue of the photolyase/blue light photoreceptor (13). Protein phosphatase 5 has also been shown to associate in vivo with heat shock protein 90 in complexes with glucocorticoid receptors (14, 15), and overexpression of the TP...

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Section: Methodsmentioning

confidence: 99%

The Tetratricopeptide Repeat Domain and a C-terminal Region Control the Activity of Ser/Thr Protein Phosphatase 5

Sinclair¹,

Borchers²,

Parker³

et al. 1999

Journal of Biological Chemistry

111

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“…The output of a binary gradient capillary HPLC (1100 Capillary LC, Agilent, Wilmington, DE) was fed through a T-based flow splitter [38] for an approximate 10:1 reduction of flow rate. The HPLC was adjustable so that the through-tip flow rate was between 200 to 500 nL/min for 50% ACN.…”

Section: Mobile Phase Deliverymentioning

confidence: 99%

Automated orthogonal control system for electrospray ionization

Valaskovic¹,

Murphy²,

Lee³

2004

J. Am. Soc. Mass Spectrom.

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Low-flow electrospray ionization is typically a purely electrostatic method, used without supporting sheath-gas nebulization. Complex spray morphology results from a large number of possible spray emission modes. Spray morphology may assume the optimal Taylor cone-jet spray mode under equilibrium conditions. When coupling to nanobore gradient elution chromatography, however, stability of the Taylor cone-jet spray mode is compromised by the gradient of mobile phase physiochemical properties. The common spray modes for aqueous/ organic mobile phases were characterized using orthogonal (strobed illumination) transmitted light and (continuous illumination) scattered light imaging. Correlation of image sets from these complementary illumination methods provides the basis for spray mode identification using qualitative and quantitative image analysis. An automated feedback-controlled electrospray source was developed on a computer capable of controlling electrospray potential using an image-processing based algorithm for spray mode identification. The implementation of the feedback loop results in a system that is both self-starting and self-tuning for a specific spray mode or modes. Thus, changes in mobile phase composition and/or flow rate are compensated in real-time and the source is maintained in the cone-jet or pulsed cone-jet spray modes. [7]. The principal means of increasing the operable ESI flow rate was with the addition of either coaxial or cross flow sheath gas to aid in the droplet formation suitable for ion generation and mass analysis [8 -10].While much research and development effort was aimed at increasing electrospray's operable flow rate, a number of groups conducted studies at lower flow rates [11][12][13][14]. Early observations by Gale and Smith [11] showed that the flow rate could be reduced to 200 nL/min without reducing the signal-to-noise (S/N) ratio. Wilm and Mann [12,15] demonstrated that flow rates could be reduced another order of magnitude, to the 10 to 20 nL/min level, with no significant reduction in S/N. At approximately the same time, Emmet and Caprioli [13] demonstrated exceptionally high sensitivity for peptide analysis by directly coupling nanobore (50 -100 m inside diameter) LC columns to low-flow (100 -200 nL/min) ESI. Ultra-low flow rates of less than 1 nL/min have been shown to yield significant ion current suitable for MS [14,16] and enable the direct coupling of small bore (Ϸ5 m) capillary electrophoresis, with sub-attomole sensitivity [17]. Collectively, these various nanoliter-per-minute ESI-MS methods have become known as nanospray.Recent experiments suggest that operation at nanospray flow rates effect ionization on a fundamental level. Ionization effects have been observed for both off-line [18,19] and on-line [20] nanospray methods. It is important to note that electrostatic attraction between mobile phase and counter-electrode is typically the sole source of mobile phase flow for off-line nanospray [12,

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“…In a review paper in 1994, Tomer et al [249] summarized a large number of publications dealing with capillary LC-MS. In this paper, two recently published examples will be discussed.…”

Section: Continuous-flow Fast Atom Bombardmentmentioning

confidence: 99%

“…Primarily, applications of capillary and nanoscale LC-ESI-MS have been in protein and peptide analysis. An extensive overview of ESI-MS in conjunction with capillary and nanoscale LC has been given in the literature [249]. In Section 7, some selected examples will be discussed, demonstrating the successful use of microcolumn LC-ESI-MS.…”

Section: Electrospray Ionizationmentioning

confidence: 99%

Microcolumn liquid chromatography: instrumentation, detection and applications

Vissers¹,

Claessens

Cramers

1997

Journal of Chromatography A

208

101

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This review discusses many different aspects of microcolumn liquid chromatography (LC) and reflects the areas of microcolumn LC research interest over the past decades. A brief theoretical discussion on a number of major issues, such as column characterisation, chromatographic dilution effects and extracolumn band broadening in microcolumn LC is given. Recent progress in column technology and the demands and developments of instrumentation and accessories for microcolumn LC are also reviewed. Besides that, the developments in a large number of established and also more recent detection techniques for microcolumn LC are also discussed. The potential of hyphenation of microcolumn LC with other techniques, more particularly of multidimensional chromatography and microcolumn LC coupled to mass spectrometry is reviewed. Finally, the perspective of microcolumn LC separation methods is stressed by a number of relevant applications.

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Capillary liquid chromatography/mass spectrometry

Cited by 73 publications

References 110 publications

The Tetratricopeptide Repeat Domain and a C-terminal Region Control the Activity of Ser/Thr Protein Phosphatase 5

The Tetratricopeptide Repeat Domain and a C-terminal Region Control the Activity of Ser/Thr Protein Phosphatase 5

Automated orthogonal control system for electrospray ionization

Microcolumn liquid chromatography: instrumentation, detection and applications

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