Carol A. Haney

Investigation of MALDI-TOF Mass Spectrometry of Diverse Synthetic Metalloporphyrins, Phthalocyanines and Multiporphyrin Arrays

We investigated the utility of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for analyzing porphyrinic compounds using a variety of different synthetic porphyrins, azaporphyrins, phthalocyanines and multiporphyrin arrays. Comparisons of spectra obtained from these analytes deposited either as neat samples or codeposited with neutral or acidic matrices have been made with the goal of identifying conditions that yield minimal demetalation, transmetalation, adduct formation and fragmentation. It was found that the molecular masses of many porphyrins can be successfully measured from neat sample preparations and do not require a matrix to facilitate desorption and ionization, although the measurement of large multiporphyrin arrays was facilitated by the use of matrices. Demetalation of magnesium porphyrins occurred in the presence of acidic matrices, but not with neutral matrices such as 1,4-benzoquinone. Positive ion spectra were obtained for each compound and ne...

Biosynthesis of triacylglycerols containing ricinoleate in castor microsomes using 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine as the substrate of oleoyl-12-hydroxylase

We have examined the biosynthetic pathway of triacylglycerols containing ricinoleate to determine the steps in the pathway that lead to the high levels of ricinoleate incorporation in castor oil. The biosynthetic pathway was studied by analysis of products resulting from castor microsomal incubation of 1-palmitoyl-2-[14C]oleoyl-sn-glycero-3-phosphocholine, the substrate of oleoyl-12-hydroxylase, using high-performance liquid chromatography, gas chromatography, mass spectrometry, and/or thin-layer chromatography. In addition to formation of the immediate and major metabolite, 1-palmitoyl-2-[14C]rici-noleoyl-sn-glycero-3-phosphocholine, 14C-labeled 2-linoleoyl-phosphatidylcholine (PC), and 14C-labeled phosphatidylethanolamine were also identified as the metabolites. In addition, the four triacylglycerols that constitute castor oil, triricinolein, 1,2-diricinoleoyl-3-oleoyl-sn-glycerol, 1,2-diricinoleoyl-3-linoleoyl-sn-glycerol, 1,2-diricinoleoyl-3-linolenoyl-sn-glycerol, were also identified as labeled metabolites in the incubation along with labeled fatty acids: ricinoleate, oleate, and linoleate. The conversion of PC to free fatty acids by phospholipase A2 strongly favored ricinoleate among the fatty acids on the sn-2 position of PC. A major metabolite, 1-palmitoyl-2-oleoyl-sn-glycerol, was identified as the phospholipase C hydrolyte of the substrate; however, its conversion to triacylglycerols was blocked. In the separate incubations of 2-[14C]ricinoleoyl-PC and [14C]ricinoleate plus CoA, the metabolites were free ricinoleate and the same triacylglycerols that result from incubation with 2-oleoyl-PC. Our results demonstrate the proposed pathway: 2-oleoyl-PC. Out results demonstrate the proposed pathway: 2-oleoyl-PC→2-ricinoleoyl-PC→ricinoleate →triacylglycerols. The first two steps as well as the step of diacylglycerol acyltransferase show preference for producing ricinoleate and incorporating it in triacylglycerols over oleate and linoleate. Thus, the productions of these triacylglycerols in this relatively short incubation (30 min), as well as the availability of 2-oleoyl-PC in vivo, reflect the in vivo drive to produce triricinolein in castor bean.

Determination of the regiochemistry of insect epoxide hydrolase catalyzed epoxide hydration of juvenile hormone by 18O-labeling studies

Abstract The regiochemistry of Trichoplusia ni epoxide hydrolase catalyzed epoxide hydration of insect juvenile hormone (JH) III has been determined by GC/MS studies of 18O-label incorporation. Nucleophilic addition occurs at C10 of the C10,11 epoxide of JH III. The identification of isotopically labeled and unlabeled diol from the enzyme catalyzed hydration reaction in H218O implies that a covalently bound ester intermediate may be involved in the mechanism of the reaction.

Field desorption mass spectral analysis of some nonmutagenic benzidine-based pigments

Abstract This paper is concerned with field desorption mass spectral (FDMS) analysis of novel disazomethine, disazoacetoacetanilide (diarylide) and disazopyrazolone pigments containing nonmutagenic benzidine homologs. The FD spectra of the aforementioned types of pigments are characterized by intense parent ion peaks [M +. ] and relatively intense [M + ]/2 daughter ions, a pattern which serves as a fingerprint for these molecular structures.

Mycotoxigenic isolates and toxin production on buckwheat and rice hulls used as bedding materials

SummaryA pre-evaluation of the samples of both buckwheat and rice hulls, planned for use as pillow fill-materials, showed the presence ofAspergillus flavus, A glaucus, andPenicillium spp. Buckwheat- and rice-hull media (BHM and RHM) inoculated withA. flavus both supported the production of aflatoxins (AFB1 and AFG1) in the parts per million (ppm) range; BHM yielded approximately twice the quantity of both AFB1 and AFG1 than did RHM. Both BHM and RHM inoculated withFusarium tricinctum yielded trichothecenes (T-2 toxins) in the ppm range, with the BHM producing approximately three times more T-2 toxins than the RHM. Also,F. tricinctum grown on both media produced several metabolites which included HT-2, 3′-OH T-2, neosolariol, T-2 triol, and T-2 tetraol. The BHM yielded all of the above, while the RHM failed to support the production of the 3′-OH T-2 toxin. In addition, neither medium inoculated withMyrothecium roridum yielded any detectable levels of macrocyclic trichothecenes. The results indicated that these materials have the potential to become contaminated with mycotoxins.

An Examination of the Coordination Chemistry of L2Pt(1,2-DITHIOLENES) Using Atmospheric Pressure Chemical Ionization Mass Spectrometry

Abstract Atmospheric pressure chemical ionization mass spectrometry (APCI–MS) has been utilized in the characterization of two series of platinum dithiolene complexes, (COD)Pt(dt) 1, (COD)–Pt(edt) 2, (COD)Pt(dmid) 3, (COD)Pt(mnt) 4, (COD)Pt(eddo) 5, (COD)Pt(dddt) 6 and (Ph3P)2Pt(dt) 7, (Ph3P)2Pt(edt) 8, (Ph3P)2Pt(dmid) 9, (Ph3P)2Pt(dmit) 10, (Ph3P)2Pt(mnt) 11 (where COD = 1,5–cyclooctadiene, dt = ethane–1,2–dithiolate, edt = ethylene–1,2–dithiolate, dmid = 1,3–dithiole–2–oxo–4,5–dithiolate, dmit = 1,3–dithiole–2–thione–4,5–dithiolate, mnt = maleonitrile–1,2–dithiolate, eddo = 4–(ethylene–1′,2′–dithiolate)–1,3-dithiole–2–one, and dddt = 5,6–dihydro–1,4–dithiin–2,3–dithiolate). The series that contains triphenylphosphine is labile toward the loss of HPPh3 +. In addition, an orthometallated species involving the platinum and triphenylphosphine is identified. A dimer is identified for 2, which is shown to be a product of the experiment and not present in the parent material. In addition, a 1:1 adduct with NH4 + is identified for 4 and 11 where the NH4 + originates from the acid hydrolysis of acetonitrile. Finally, a highly unique ion, Pt+, a bare platinum ion, is observed in all COD complexes indicating that a radical mechanism must accompany the decomposition of the COD complexes during the fragmentation process.

Reactions of F2+• with aromatic compounds in an ion trap mass spectrometer

Abstract The reaction of F2+• with aromatic compounds in the gas phase has been shown to proceed by way of two competing reactions: single electron transfer and addition-elimination.