Biomedical subjects

Sanford P Markey

Publications and source records attributed to Sanford P Markey.

7 recordsLinked to original sources

PubMed2006

Nitration and inactivation of IDO by peroxynitrite.

IDO induction can deplete L-tryptophan in target cells, an effect partially responsible for the antimicrobial activities and antiallogeneic T cell responses of IFN-gamma in human macrophages, dendritic cells, and bone marrow cells. L-tryptophan depletion and NO production are both known to have an antimicrobial effect in macrophages, and the interaction of these two mechanisms is unclear. In this study we found that IDO activity was inhibited by the peroxynitrite generator, 3-(4-morpholinyl)sydnonimine, in PMA-differentiated cytokine-induced THP-1 (acute monocytic leukemia) cells and IFN-gamma-stimulated PBMCs, whereas IDO protein expression was unaffected compared with that in untreated cells. Nitrotyrosine was detected in immunoprecipitated (IP)-IDO from PMA-differentiated cytokine-induced THP-1 cells treated with 3-(4-morpholinyl)sydnonimine, but not from untreated cells. Treatment of IP-IDO and recombinant IDO (rIDO) with peroxynitrite significantly decreased enzyme activity. Nitrotyrosine was detected in both peroxynitrite-treated IP-IDO and rIDO, but not in either untreated IP-IDO or rIDO. Peptide analysis by liquid chromatography/electrospray ionization and tandem mass spectrometry demonstrated that Tyr15, Tyr345, and Tyr353 in rIDO were nitrated by peroxynitrite. The levels of Tyr nitration and the inhibitory effect of peroxynitrite on IDO activity were significantly reduced in the Tyr15-to-Phe mutant. These results indicate that IDO is nitrated and inactivated by peroxynitrite and that nitration of Tyr15 in IDO protein is the most important factor in the inactivation of IDO.

Amino Acid Sequence↗

PubMed2005

Direct profiling of the cerebellum by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: A methodological study in postnatal and adult mouse.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI MS) can detect substantial changes in expression of proteins in tissues, such as cancer cells. A more challenging problem is detecting the smaller changes expected in normal development or complex diseases. Here we address methodological issues regarding the acquisition and analysis of MALDI MS data from tissue sections, in a study of mouse cerebellum at different stages of development. Sections of the cerebellar cortex were analyzed at the peak of granule neuron production [postnatal day (P) 7], during synapse formation (P14), and in adults. Data were acquired (Voyager-DEtrade mark STR Biospectrometry Workstation; seven acquisitions of 50 shots per section, 3.5-50 kDa), preprocessed (Data Explorer 4.3), and averaged. Among 846 peaks detected, in at least 50% of at least one group, 122 showed significant group differences (Kruskal-Wallis ANOVA) after Bonferroni correction. Factor analyses revealed two age-related factors, possibly reflecting gradients of expression during development. Predictive analysis of microarrays generated a model from half of the sample that correctly predicted developmental groups for the second half. Intraclass correlation coefficients, measuring within-mouse consistency of peak heights from three tissue sections, were acceptable at lower m/z and for larger peaks at higher m/z. Low mass was the best predictor of significant group differences. The analysis demonstrates that MALDI MS of normal tissue sections at different ages can detect consistent, significant group differences. Further work is needed to increase the sensitivity of the methods and to apply them reliably to brain regions and to subproteomes with relevance to diverse brain functions and diseases.

Age Factors↗

PubMed2005

Fully automated micro- and nanoscale one- or two-dimensional high-performance liquid chromatography system for liquid chromatography-mass spectrometry compatible with non-volatile salts for ion exchange chromatography.

A one- or two-dimensional high performance liquid chromatography system for electrospray ionization mass spectrometers has been developed that is optimized for ion exchange and reversed phase separations. A unique and simple valve configuration permits the use of a variety of non-volatile salts; ammonium sulfate was used in an example of strong cation exchange separations. The system was designed and evaluated for both micro- and nanoflow chromatography. The peptide detection limit was approximately 100 fmol for micro- and 20 fmol for nanoflow, demonstrating the concentration and mass sensitivity improvements expected with nanoelectrospray ionization. The 1D/2D-HPLC MS system is fully automated for routine peptide analyses, compatible with direct injection of proteolytic digests, and exhibits chromatographic reproducibility and sensitivity. Software permits operator selection of either a 1D or 2D configuration with corresponding system parameters as required for individual samples. The hardware elements and resulting performance are described in this paper.

Automation↗

PubMed2004

Characterizing complex peptide mixtures using a multi-dimensional liquid chromatography-mass spectrometry system: Saccharomyces cerevisiae as a model system.

A rugged, reproducible, multi-dimensional LC-MS system was developed to identify and characterize proteins involved in protein-protein interactions and/or protein complexes. Our objective was to optimize chromatographic parameters for complex protein mixture analyses using automated peptide sequence recognition as an analytical end-point. The chromatographic system uses orthogonal separation mechanisms by employing strong cation exchange (SCX) in the first dimension and reversed phase (RP) in the second dimension. The system is fully automated and sufficiently robust to handle direct injections of protein digests. This system incorporates a streamlined post analysis results comparison, called DBParser, which permitted comprehensive evaluation of sample loading and chromatographic conditions to optimize the performance and reproducibility. Peptides obtained from trypsin digestion of a yeast soluble extract provided an open-ended model system containing a wide variety and dynamic range of components. Conditions are described that resulted in an average (n = 4) of 1489 unique peptide identifications, corresponding to 459 non-redundant protein sequence database records (SDRs) in the 20 microg soluble fraction digest.

Chromatography, Liquid↗

PubMedDate not supplied

Assessing data quality of peptide mass spectra obtained by quadrupole ion trap mass spectrometry.

An algorithm is introduced to assess spectral quality for peptide CID spectra acquired by a quadrupole ion trap mass spectrometer. The method employs a quadratic discriminant function calibrated with manually classified 'bad' and 'good' quality spectra, producing a single 'spectral quality' score. Many spectra examined that do not have significant matches are assessed to have good spectral quality, indicating that advances in search methods may yield substantial improvements in results.

Amino Acid Sequence↗

PubMedDate not supplied

DBParser: web-based software for shotgun proteomic data analyses.

We describe a web-based program called 'DBParser' for rapidly culling, merging, and comparing sequence search engine results from multiple LC-MS/MS peptide analyses. DBParser employs the principle of parsimony to consolidate redundant protein assignments and derive the most concise set of proteins consistent with all of the assigned peptide sequences observed in an experiment or series of experiments. The resulting reports summarize peptide and protein identifications from multidimensional experiments that may contain a single data set or combine data from a group of data sets, all related to a single analytical sample. Additionally, the results of multiple experiments, each of which may contain several data sets, can be compared in reports that identify features that are common or different. DBParser actively links to the primary mass spectral data and to public online databases such as NCBI, GO, and Swiss-Prot in order to structure contextually specific reports for biologists and biochemists.

Amino Acid Sequence↗

PubMedDate not supplied

Open mass spectrometry search algorithm.

Large numbers of MS/MS peptide spectra generated in proteomics experiments require efficient, sensitive and specific algorithms for peptide identification. In the Open Mass Spectrometry Search Algorithm (OMSSA), specificity is calculated by a classic probability score using an explicit model for matching experimental spectra to sequences. At default thresholds, OMSSA matches more spectra from a standard protein cocktail than a comparable algorithm. OMSSA is designed to be faster than published algorithms in searching large MS/MS datasets.

Algorithms↗