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  • 1
    Electronic Resource
    Electronic Resource
    Ethane elimination from C11H24+. isomers. The effect of the position of formation of the neutral in relation to the ionic partner on the competitiveness of ion/neutral complex-mediated eliminations (1991)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 357-358 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Competition between loss of ethyl and ethane elimination through [C2H·5 C9H19+] complexes is assessed as a function of the initial location of the two partners relative to each other. Ethyl loss is favored when that species originates from near the end of the chain, but ethane elimination increases steadily in relative importance as the site of cleavage is shifted towards the middle of the chain and is dominant when the ethyl is cleaved from the middle carbon. It is speculated that when the center-of-charge and the center-of-mass of the complex are substantially away from each other, individual rotation of the partners causes the ethyl group to spend relatively litle time near the hydrogen atoms it can abstract, favoring simple dissociation over ethane elimination. When the two centers approximately coincide, it is supposed that the ethyl group spends much of its time near abstractable hydrogen atoms, favoring ethane elimination.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290050805
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  • 2
    Electronic Resource
    Electronic Resource
    Added evidence for an intermediate enol-ion/olefin-ion/neutral complex in the loss of a methyl group from ionized 2-hexanone (1988)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 132-134 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290020703
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  • 3
    Electronic Resource
    Electronic Resource
    Transforming growth factor-β regulation of retinoblastoma gene product and E2F transcription factor during cell cycle progression in mouse fibroblasts (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 160 (1994), S. 1-9 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanism by which transforming growth factor beta (TGFβ) exerts growth stimulatory effects was examined in C3H/10T1/2 mouse fibroblasts by study of cell cycle regulation of the retinoblastoma gene product (p110Rb) and transcriptional regulation of the p110Rb-associated transcription factor, E2F. Northern blotting analysis shows that TGFβ and/or epidermal growth factor (EGF) stimulate by three to sixfold the level of Rb mRNA which is also reflected by the increased levels of p110Rb. p110Rb becomes phosphorylated in mid-G1 and further phosphorylated at the G1/S transition. Hyperphosphorylation of p110Rb by TGFβ can be observed when cells are in S phase. TGFβ stimulates by three to fourfold the activity of cdk2 kinase consistent with the observed phosphorylation of p110Rb and also with the possibilit that the kinase is involved in phosphorylating p110Rb close to the G1/S transition. Thus, TGFβ as a growth stimulator induces, as does EGF, the phosphorylation of p110Rb during cell cycle progression. Transient transfection of E2F promoter constructs was used to analyze the effect of TGFβ on the modulation of E2F-mediated transcription. The data revealed that TGFβ can stimulate wild-type adenoviral E2 promoter activity by 12-fold. Taken together, TGFβ-induced phosphorylation of p110Rb in mouse fibroblasts appears to exert a positive regulatory function upon genes that have a pivotal role in the G1/S transition of the cell cycle. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041600102
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  • 4
    Electronic Resource
    Electronic Resource
    Identification of methotrexate and folic acid analogs by mass spectrometryAbbreviation: APA = A-amino-4-deoxypteroic acid. (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1978), S. 161-163 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methotrexate and folic acid analogs are polar molecules and attempts to obtain electron impact and chemical ionization mass spectra of these compounds by several laboratories have failed. We have found that methylation of this important class of compounds with diazomethane produces derivatives which are sufficiently volatile to allow their mass spectra to be recorded. The mass spectra of the methyl derivatives of five compounds, 4-amino-4-deoxy-N10-methylpteroylglutamic acid, 4-amino-4-deoxypteroylglutamic acid, pteroylglutamic acid, 4-amino-4-deoxypteroic acid and N10-methylpteroylglutamic acid are presented, and the fragmentation pathways of these compounds discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200050211
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  • 5
    Electronic Resource
    Electronic Resource
    Revertants of selfing (gad) mutants in Physarum polycephalum (1981)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981), S. 253-267 
    Details
    ISSN: 0192-253X
    Keywords: myxomycete ; Physarum polycephalum ; mating type ; sexual compatibility ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The conversion of the uninucleate amoebal form of Physarum polycephalum to the multi-nucleate plasmodial form is under the control of a genetic region which contains matA (or mt), a determinant of mating specificity. The region is the site of most gad mutations, which give amoebae the ability to produce plasmodia in clones without mating (ie, to self). In the present study, nonselfing revertants were isolated from two matA2-derived gad mutants and two matA3-derived gad mutants. Some revertants were found to have regained exactly, or nearly, the same phenotype as the original matA2 or matA3 strain. Others expressed new mating types, having gained the ability to mate with strains of the parental matA type. The results are compatible with a model in which new mating types arise from forward mutations (gad) and back mutations (npf or no plasmodium formation) occurring successively in a single gene, matA.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020020304
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  • 6
    Electronic Resource
    Electronic Resource
    Origin of the [C4H9O]+ ions in the mass spectrum of n-butyl ethyl ether (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 109-113 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanisms of formation of m/z 73 ions in the mass spectrum of the ionized title compound were investigated by deuterium substitution and by examining the decompositions of metastable ions. Two routes to the [C4H9O]+ ions were found in the normal spectrum. The ethyl lost by the major pathway contains the α- and β-hydrogens and a γ-hydrogen from the butyl group. The minor route involves the loss of ethylene from the [M—H]+ ion. There were metastable peaks for losses of ethyl, ethanol and methyl from the molecular ion. The ethyl contains the α- and β-methylenes and a γ-hydrogen, while the methyl is the δ-methyl of the butyl group. The labeling data rule out a previous mechanistic proposal for the loss of ethyl and support a mechanism involving stepwise isomerization to the sec-butyl ethyl ether molecular ion. However, the metastable ion chemistries of the molecular ions from the n- and sec-butyl ethyl ethers are highly dissimilar, perhaps due to decompositions from different electronic states. The n-pentyl methyl ether ions loses both ethyl and propyl, apparently following rearrangements to the 3-pentyl and 2-pentyl ether ions. Di n-butyl and n-butyl methyl ethers also give metastable peaks for loss of methyl, ethyl and the shorter chain alcohol.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210140210
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  • 7
    Electronic Resource
    Electronic Resource
    The formation of [CH3CH2C(=OH)CH2]+· from 1-hepten-3-ol (1981)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1981), S. 294-296 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [C4H8O]+· ion in the mass spectrum of 1-hepten-3-ol is shown to be \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} {\rm{CH}}_{\rm{2}} {\rm{C(= }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H}})\mathop {\rm{C}}\limits^{\rm{.}} {\rm{H}}_{\rm{2}} $\end{document} by collisional activation spectra, appearance energies and comparison of the ratios of the intensities of metastable decompositions. [C4H8O]+· appears to be formed by rearrangement of ionized 1-hepten-3-ol to \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} \mathop {\rm{C}}\limits^{\rm{.}} {\rm{HC(= }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H)CH}}_{\rm{2}} {\rm{CH}}_{\rm{2}} {\rm{CH}}_{\rm{2}} {\rm{CH}}_{\rm{3}} $\end{document} followed by γ-hydrogen rearrangement-β-cleavage.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210160704
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  • 8
    Electronic Resource
    Electronic Resource
    Propanoyl ion formation from metastable [C3H6O]+· ions (1982)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1982), S. 366-368 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collisionally activated spectra demonstrate that CH3CH2C≡O+ rather than \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 2} = {\rm CHCH = }\mathop {\rm O}\limits^{\rm + } {\rm H}$\end{document} is formed in the metastable losses of hydrogen from [C3H6O]+· ions with the oxygen on the first carbon. This provides another example of formation of an acyl ion following ‘ketonization’ prior to metastable decomposition.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210170804
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  • 9
    Electronic Resource
    Electronic Resource
    The decompositions of metastable [C4H8O]+· ions and the [C4H8O]+· potential surface (1983)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1983), S. 466-473 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collisionally activated decomposition (CA) spectra of [C4H8O]+· ions and the products of their metastable decompositions are used to refine a previously presented picture of the reactions of [C4H8O]+· ions. Metastable [C4H8O]+· isomers predominantly rearrange to the 2-butanone ion and decompose by loss of methyl and ethyl, although up to 38% of the methyl losses take place by other pathways to form \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{2}} = {\rm{CHCH = }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H}}{\rm{.}} $\end{document} . The CA spectra of many of the [C4H8O]+· ions with the oxygen on the first carbon are very similar, consistent with those ions isomerizing largely to common structures before or after collision. However, several of these ions have unique CA spectra, so they must remain structurally distinct from the majority of the [C4H8O]+· ions below energies required for decomposition. The CA spectra of ions with the oxygen on the second carbon are distinct from those of ions with the oxygen on the first carbon, so there is limited interconversion of the non-decomposing forms of the two types of ions. A potential energy diagram for the reactions of metastable [C4H8O]+· ions is constructed from appearance energy measurements. As would be expected, the relative importances of most of the [C4H8O]+· isomerizations seem to be inversely related to the activation energies for those processes. Some parallels between the isomerizations of [C4H8O]+· ions and those of related ions are pointed out.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210181104
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  • 10
    Electronic Resource
    Electronic Resource
    Formation of ketone ions upon the loss of CH2O from ionized esters (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 2-3 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Unimolecular and collision-induced decompositions of the products of CH2O loss from propyl propanoate and butyl butanoate demostrate that the respective products are the 3-pentanone and 4-heptanone ions.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210200103
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