Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Electron capture dissociation at 86 K of the linear peptide Substance P produced just two backbone fragments, whereas at room temperature eight backbone fragments were formed. Similarly, with the cyclic peptide gramicidin S, just one backbone fragment was formed at 86 K but five at room temperature. The observation that some backbone scissions are active and others inactive, when all involve NC(alpha) cleavages and have a high rate constant, indicates that the more specific fragments at low temperatures reflects the reduced conformation heterogeneity at low temperatures. This is supported by reduced or inactive hydrogen loss, a channel that has previously been shown to be affected by conformation. The conclusion that the ECD fragments are a snapshot of the conformational (intramolecular solvation shell) heterogeneity helps explain how the relative intensities of ECD fragments can be different on different instrument and highlights the common theme in methodologies used to increase sequence coverage, namely an increase in the conformational heterogeneity of the precursor ion population.
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PMID:Electron capture dissociation at low temperatures reveals selective dissociations. 1558 63

To evaluate the difference of POPs atrazine degradation dynamics in soils under different fertilization conditions, we set up an analysis method of the atrazine residue in soils and studied residue dynamics of atrazine in soils under a long-term located fertilization conditions. After extracted by surging with acetone, liquid-liquid partition and eluted through florisil, the residue of atrazine in soils was detected by gas chromatogram with 63Ni-ECD. The minimum detectable quantity of atrazine is 6.4 x 10(-12) g and the minimum detectable concentration is 6.4 x 10(-9) g x kg(-1) in the soil. The spiked recoveries of atrazine with the three concentration of 0.11, 1.1, 11.0 mg x kg(-1) in soils are 91.41% +/- 4.36%, 93.58% +/- 4.54%, 90.35% +/- 3.59%, according with the request of pesticide residue analysis. The degradation of atrazine in soil under a long-term located fertilization conditions was studied. The results show the degradation of atrazine follows stair dynamic equation, and the degradation half-life of atrazine in soils fertilized with CK, NPK, NPK + M, NPK + S are 20.6, 23.0, 28.5, 33.2 d, respectively. Subjected to analysis of LSR, NPK and organic fertilizers are obviously propitious to the degradation of atrazine. The separate regression and stepwise regression analysis prove the degradation half-life of atrazine in soils is well related with the content of alkaline nitrogen, organic matter and total nitrogen, and the coefficients are 0.9983, 0.9826 and 0.9521, respectively. Maybe the reason is that these soil nutrient substance offers enough the element carbon and nitrogen for action of microbe, and the higher action of microbe quickens the degradation of atrazine in soils.
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PMID:[Degradation dynamics of POPs atrazine in soils under long-term located fertilization conditions]. 1829 Apr 44

We introduce a new atmospheric pressure-electron capture dissociation (AP-ECD) source in which conventional nanospray emitters are coupled with the source block and photoionization lamp of a PhotoSpray APPI source. We also introduce procedures for data collection and processing, aimed at maximizing the signal-to-background ratio of ECD products. Representative data from Substance P are presented to demonstrate the performance of the technique. Further, we demonstrate the effects of two important experimental variables, source temperature and vacuum-interface declustering potential (DP), on the method. Last, we show that even when a high source temperature is used to maximize efficiency, AP-ECD fragments of a model phosphorylated peptide retain the modification.
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PMID:A new ion source and procedures for atmospheric pressure-electron capture dissociation of peptides. 2195 83

Atmospheric pressure electron capture dissociation (AP-ECD) is an emerging technique with the potential to be a more accessible alternative to conventional ECD/electron transfer dissociation (ETD) methods because it can be implemented using a stand-alone ion source device suitable for use with any existing or future electrospray ionization mass spectrometer. With AP-ECD, no modification of the main instrument is required, so it may easily be retrofitted to instruments not originally equipped with ECD/ETD capabilities. Here, we present our first purpose-built AP-ECD source and demonstrate its use in conjunction with capillary LC for the analysis of substance P, a tryptic digest of bovine serum albumin, and a phosphopeptide mixture. Quality ECD spectra were obtained for all the samples at the low femtomole level, proving that LC-AP-ECD-MS is suitable for the structural analysis of peptides and protein digests, in this case using an unmodified quadrupole time-of-flight mass spectrometer built ca. 2002.
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PMID:Liquid chromatography-atmospheric pressure electron capture dissociation mass spectrometry for the structural analysis of peptides and proteins. 2249 41