Tandem quadrupole-Fourier transform mass spectrometry of oligopeptides.
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Fourier Analysis↗
Biomedical subjects
D F Hunt
Publications and source records attributed to D F Hunt.
alpha-Tocopherol in the developing rat retina: a high pressure liquid chromatographic analysis.
High pressure liquid chromatography was used to measure alpha-tocopherol in the retinas of rats reared in a cyclic light or dark environment. These measurements were performed on extracts of whole retinas during the developmental period, 18-60 days, and on isolated ROS from adult animals. Similar alpha-tocopherol determinations were performed on retinas and isolated ROS following exposure of rats to intense visible light for 24 hr periods. The results show that alpha-tocopherol is chromatographically separated from the vitamin A derivatives found in the retina and is pure, as judged by mass spectrometry. In the retinas of cyclic light and dark reared rats, alpha-tocopherol accumulates in an age dependent fashion, so that at 60 days the level is nearly double that of animals at 18-20 days of age (P less than 0.001). Because the age dependent accumulation of rhodopsin is greater in dark reared rats, the average molar ratio of rhodopsin to alpha- tocopherol in the retina of dark reared animals is 25% higher than in cyclic light rats. Following exposure of rats to intense visible light for 24 hr periods, alpha-tocopherol concentrations in the retina were unchanged from the levels in control animals. In adult animals the concentration of alpha-tocopherol in ROS is 2.5-3.5 times higher than in whole retina. ROS from adult cyclic light reared rats also contain an average of 43% more alpha-tocopherol per mg protein than ROS from dark maintained animals (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
Age Factors↗
MS/MS analysis of diesel emissions and fuels treated with NO2.
Correlations between direct-acting mutagens in diesel emissions and the activity of nitroaromatic compounds have been noted, but detection and identification of nitro-compounds in diesel particulates has remained an elusive problem. In the results reported here, MS/MS (tandem mass spectrometry) was found to detect nitroaromatic compounds in fractionated and unfractionated diesel soot extracts. The nitro-compounds detected ranged from two- to four-ring polynuclear aromatic hydrocarbon derivatives and were primarily mono-nitro derivatives. An aromatic fraction from diesel fuel reacted with NO2 resembled diesel exhaust extracts from an engine operating on the same fuel. Therefore, it is possible that nitroaromatic derivatives in diesel exhaust may be in part due to unburned fuel residues reacting with NO chi formed in the combustion process. The utility of MS/MS in comparing complex mixtures from different sources or subfractions thereof is discussed.
Fuel Oils↗
Mixture analysis by triple-quadrupole mass spectrometry: metabolic profiling of urinary carboxylic acids.
In this new method for profiling urinary carboxylic acids, lyophilized urine samples are analyzed directly with a triple-quadrupole mass spectrometer. Extraction, derivatization, and lengthy gas-chromatographic separation procedures are obviated by this approach. Total sample-preparation, instrument, and data-analysis time per sample is about 15 min. More than 100 different organic acids can be detected in a typical urine sample. All components of the solid urine residue are volatilized into the ion source of the mass spectrometer and converted to (M-1)- ions by reaction with OH- under chemical ionization conditions. Quadrupole 1 is set to transmit ions of a particular m/z ratio, which in turn collide with molecular nitrogen in quadrupole 2 and dissociate to smaller charged fragments. Carboxylic acid (M-1)- ions uniquely lose either CO2 (44 atomic mass units) or both H2O and CO2 (62 atomic mass units). Quadrupole 3 is set to pass only ions that have lost either 44 or 62 atomic mass units. Accordingly, the instrument specifically detects carboxylic acids in the urine matrix and no other components. Direct analysis of polyethylene glycols and their acidic metabolites in urine and serum of a burn patient treated with an antimicrobial cream having a polyethylene glycol base is also discribed.
Adult↗
Sequence analysis of polypeptides by collision activated dissociation on a triple quadrupole mass spectrometer.
A new approach to the direct sequencing of oligopeptides in complex mixtures is described. Mixtures of [2Ho]/[2H3]-N-acetylated and N,O-permethylated peptides are analyzed by collision activate dissociation on a triple quadrupole mass spectrometer using isobutane chemical ionization. Analysis of the collision activated dissociation spectra enables peptide sequences to be deduced. Use of electron capture negative chemical ionization for the sequence analysis of neuropeptides at the picomole level is also described.
Amino Acid Sequence↗
Studies of negative ions by collision-induced decomposition and hydrogen-deuterium exchange techniques.
Development of two new techniques for studying the gas phase chemistry of negative ions is reported. Collision induced dissociation (CID) of (M-1)- ions has been accomplished in a newly constructed triple stage quadrupole mass spectrometer. This instrument was assembled by adding two additional Finnigan quadrupole mass filters to a Finnigan Model 3200 CI mass spectrometer. Generation of (M-1)- ions is accomplished by allowing OH- and sample to react under CI conditions in the ion source. The first quadrupole mass filter, Q1, is then employed to selectively pass the (M-1)- ion into a second quadrupole filter containing argon or neon at 10(-3) torr. On collision with the inert gas the (M-1)- ions dissociate into fragments which are then mass analyzed in the third quadrupole filter, CID spectra of (M-1)- ions from twelve carbonyl compounds are presented in this paper. Ion molecule isotope exchange reactions in the CI ion source can be used to count the number of hydrogen atoms in many different chemical environments. Collisions between sample (M-1)- ions and deuterium-labeled reagent gases (ND3, D2O, EtOD) facilitate incorporation of deuterium into the negative ion if the basicities of the sample and reagent anions are similar. Thus it is possible to selectively incorporate deuterium into many organic samples by controlling the exothermicity of the acid base, ion-molecule chemistry.
Anions↗
Plasma polyamines determined by negative-ion chemical ionization/mass spectrometry.
We have developed an accurate and highly sensitive gas-chromatographic/mass-spectrometric procedure for determining di- and polyamines (putrescine, spermidine, and spermine) in plasma and erythrocytes. Deuterium-labeled analogs of putrescine, spermidine, and spermine were synthesized for use as internal standards. Trifluoroacetyl derivatives of the polyamines were formed during the procedure and then detected with negative-ion chemical ionization/mass spectrometry in combination with multiple ion monitoring. Limits of sensitivity ranged from 0.25 to 1.0 pmol of analyte injected into the instrument.
Chromatography, Gas↗
Phenethyl alcohol and tryptophol: autoantibiotics produced by the fungus Candida albicans.
Two autoantibiotics produced by the fungus Candida albicans have been identified, with the aid of mass spectrometry, as 2-phenylethanol and 3-beta-hydroxyethylindole. The cyclodipeptides, cyclo(proline-leucine) and cyclo(proline-phenylalanine) were also isolated from cultures of Candida albicans, but did not inhibit the growth of the fungus.
Anti-Bacterial Agents↗
Structure elucidation of dinucleotides by mass spectrometry.
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Nucleotides↗
Identification of proctolin in the central nervous system of the horseshoe crab, Limulus polyphemus.
A proctolin-like peptide was isolated from the prosomal CNS of the chelicerate arthropod, Limulus, and purified using size exclusion, ion exchange and high performance liquid chromatography. Coincident bioassay (cockroach hindgut) and radioimmunoassay were employed to identify fractions which contained proctolin-like material. Proctolin-like activity coeluted with synthetic proctolin with all three chromatographic techniques employed. When applied to either the Limulus heart or hindgut preparations, purified Limulus proctolin produced excitatory responses which were indistinguishable from those produced by the synthetic peptide. Purified samples of the Limulus proctolin-like peptide were subjected to Edman degradation and tandem mass spectrometry and the amino acid sequence of the Limulus peptide was determined to be identical to that of cockroach proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH). The presence of proctolin in the Limulus CNS and its biological action on the isolated heart and hindgut suggest a physiological role for this peptide in the regulation of cardiac output and hindgut motility.
Amino Acid Sequence↗
Primary structure of the major isomorph of the crustacean hyperglycemic hormone (CHH-I) from the sinus gland of the Mexican crayfish Procambarus bouvieri (Ortmann): interspecies comparison.
The amino acid sequence of this neuropeptide was elucidated by means of a combined approach of enzymatic digestions, manual and automatic Edman degradations, and mass spectrometry. It is a 72 residue peptide (molecular mass 8388 Da), with six cysteines forming three disulfide bridges connecting residues 7-43, 23-39, and 26-52, with blocked N- and C-termini, and lacking the amino acids histidine, methionine, and tryptophan. The CHH-I of Procambarus bouvieri is compared with the other known CHHs from Orconectes limosus (98.6% identity), Homarus americanus isomorph A (83.3% identity), Homarus americanus isomorph B (79.2% identity), and Carcinus maenas (61.1% identity).
Amino Acid Sequence↗
Detection of nitroaromatic compounds on coal combustion particles.
Mutagenic and nonmutagenic extracts of fly ash from fluidized bed combustion were analyzed to determine the compounds responsible for the direct mutagenic activity (mutagenic activity that does not require added metabolic enzymes in the Salmonella mutagenicity assay). Some nitro derivatives of polycyclic aromatic hydrocarbons which are direct acting mutagens were detected by tandem triple quadrupole mass spectrometry. Treatment of a mutagenic and a nonmutagenic extract with excess N2O4 resulted in 28- and 3200-fold increases, respectively, in direct mutagenicity in Salmonella typhimurium strain TA98 and an increase in the relative abundance of nitroaromatic compounds. Polycyclic aromatic compounds were also detected and tentatively identified by gas chromatography-mass spectrometry. Since, previous studies have shown that polycyclic aromatic hydrocarbons may react with NO2 to form direct-acting mutagens, it appears that the direct-acting mutagens in these fly ash extracts may be products of reactions of polycyclic aromatic hydrocarbons with NOX in the combustion gases.
Coal↗
Postvasectomy alterations in protein synthesis and secretion in the rat caput epididymidis are not repaired after vasovasostomy.
Many men who have undergone vasectomy later request vasovasostomy. Unfortunately, significant numbers of these men remain infertile despite the reestablishment of patent ducts. This report examines the possibility that epididymal function remains compromised after vasovasostomy in the rat by examination of quantifiable, in vivo protein synthesis and secretion in the caput epididymidis. Rats were studied 30 days after vasectomy, 30 days after a vasovasostomy (which was performed 30 days after vasectomy), or after sham operations. Epididymal lumen fluids (LF) were collected by micropuncture after 3 hours' in vivo microperifusion of tubules with 35S-amino acids. Proteins were separated by 2-dimensional electrophoresis and were detected by Coomassie blue staining. Synthesized proteins in tubule extract and synthesized and secreted proteins in LF were detected by autoradiography and image analysis. Specific proteins that appeared to be affected by vasectomy-vasovasostomy were identified by internal sequence analysis. LF contained an average of 87 detectable proteins synthesized and secreted in the control caput. Nineteen of the most prominent LF proteins were selected for more focused study. The most prominent proteins were clusterin, cysteine-rich secretory protein (CRISP)-1, and epididymal retinoic acid-binding protein. Among these, CRISP-1 remained reduced in LF after vasovasostomy. Two more minor proteins that remained reduced after vasovasostomy were identified as prostaglandin D2 synthase and phosphatidylethanolamine-binding protein. All 3 of these proteins occur in the epididymides of multiple species and have been associated with sperm fertilizing capacity.
Animals↗