scholarly journals Phycocyanobilin synthesis in the unicellular rhodophyte Cyanidium caldarium

1978 ◽  
Vol 172 (3) ◽  
pp. 569-576 ◽  
Author(s):  
R F Troxler ◽  
P Kelly ◽  
S B Brown
Keyword(s):  
Absorption Spectrum ◽  
Mass Spectrum ◽  
Electronic Absorption ◽  
Bile Pigment ◽  
Cyanidium Caldarium ◽  
Pigment Synthesis ◽  
Structural Identity ◽  
Electron Impact Mass ◽  
Impact Mass

Light is required for synthesis of the accessory photosynethetic pigment phycocyanin in cells of the unicellular rhodophyte Cyanidium caldarium. Phycocyanin is a conjugated protein composed of polypeptide subunits to which the light-absorbing bile pigment chromophore phycocyanobilin is covalently attached. Dark-grown cells of C. caldarium are unable to make phycocyanin, but when incubated in the dark with 5-aminolaevulinate the cells synthesize and excrete a protein-free phycobilin (algal bile pigment) into the suspending medium. The electronic absorption spectrum, electron impact mass spectrum, chromatographic properties and imide products obtained after chronic acid degradation of the excreted phycobilin were identical with those of phycocyanobilin cleaved from phycocyanin in boiling methanol. This establishes the structural identity between the excreted phycobilin, which is the end product of bile-pigment synthesis in vivo, and the chromophore cleaved from phycocyanin in boiling methanol. The significance of the structure of the excreted phycobilin with respect to the events surrounding the assembly of the phycocyanin molecule in vivo is discussed.

Electron Impact Mass Spectroscopy for Identification of Phencyclidine

1986 ◽  
Vol 69 (5) ◽  
pp. 814-820
Author(s):  
Charles C Clark
Keyword(s):  
Mass Spectrum ◽  
High Resolution ◽  
Electron Impact ◽  
Mass Spectroscopy ◽  
Phenyl Ring ◽  
Labeled Compounds ◽  
Electron Impact Mass ◽  
High Resolution Mass Spectroscopy ◽  
Impact Mass ◽  
Resolution Mass

Abstract The electron impact mass spectrum of phencyclidine (PCP) was studied using both deuterium-labeled analogs and high-resolution mass spectroscopy. The deuterium-labeled compounds used were d5.PCP having 5 deuterium atoms on the phenyl ring, d10.PCP having 10 deuterium atoms on the cyclohexyl ring, and d15.PCP having deuterium atoms on both the phenyl and cyclohexyl rings. The identities of some major fragments and some possible pathways for their formation are shown. Electron impact mass spectroscopy is shown to be a definitive test for the identification of PCP.

scholarly journals Bile pigment synthesis in plants. Incorporation of haem into phycocyanobilin and phycobiliproteins in Cyanidium caldarium

1981 ◽  
Vol 194 (1) ◽  
pp. 137-147 ◽  
Author(s):  
S B Brown ◽  
J A Holroyd ◽  
R F Troxler ◽  
G D Offner
Keyword(s):  
Chlorophyll A ◽  
Protoporphyrin Ix ◽  
Bile Pigment ◽  
Cyanidium Caldarium ◽  
Pigment Synthesis ◽  
14C Labelling

A procedure was developed whereby haem was taken up by dark-grown cells of the unicellular rhodophyte Cyanidium caldarium. These cells were subsequently incubated either in the dark with 5-aminolaevulinate, which results in excretion of phycocyanobilin into the suspending medium or incubated in the light, which results in synthesis and accumulation of phycocyanin and chlorophyll a within the cells. Phycocyanobilin was isolated from phycocyanin by cleavage from apoprotein in methanol. Phycocyanobilin prepared from phycocyanin or excreted from cells given 5-aminolaevulinate was methylated and purified by t.l.c. By using 14C labelling either in the haem or in 5-aminolaevulinate administered, haem incorporation into phycocyanobilin was demonstrated in both dark and light systems. Since chlorophyll a synthesized in the light in the presence of labelled haem contained no radioactivity, it was clear that haem was directly incorporated into phycocyanobilin and not first converted into protoporphyrin IX. These results clearly demonstrate phycocyanobilin synthesis via haem and not via magnesium protoporphyrin IX as has also been postulated.

Spectres de masse d'hydrazino-2 benzo- et naphtothiazoles et d'hydrazones des méthyl-3 benzo- et naphtothiazolinones-2

1975 ◽  
Vol 53 (23) ◽  
pp. 3677-3680 ◽  
Author(s):  
Jean-Claude Richer ◽  
Philippe Lapointe ◽  
Martine Beljean ◽  
Michel Pays
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
Base Peak ◽  
Molecular Ion ◽  
Ion Fragmentation ◽  
Fragment Ions ◽  
Sampling Probe ◽  
Electron Impact Mass ◽  
Impact Mass ◽  
Hydrazone Form

Electron impact mass spectra are reported for the hydrazones of 3-methyl-2-benzothiazolinone (1), of 4-, 5-, 6-, and 7-chloro-3-methylbenzo-2-thiazolinones (2, 3, 4, and 5) and of 3-methyl-naphtho[2,1-d]-2-thiazolinone (6), as well as for 2-hydrazinobenzothiazole (7), for 4-, 5-, 6-, and 7-chloro-2-hydrazinobenzothiazoles (8, 9, 10, and 11) and for 2-hydrazinonaphtho[2,1-d]thiazole (12). The results obtained in the two series are compared. The 2-hydrazone and 3-methyl-benzo-2-thiazolinone and its derivatives all form a base peak corresponding to the molecular ion; fragmentation proceeds mainly by successive losses of·NH2, HCN, HCN, and then CS. Initial losses of N2H2, NH·, and NH3 are minor fragmentation routes.In the case of 2-hydrazinobenzothiazole and its derivatives, the base peak is still that of the molecular ion; however, the relative proportions of the various fragment ions vary with the position of sampling probe inside the apparatus. Thus it is concluded that the observed mass spectrum is that of a mixture of the possible hydrazone-hydrazine tautomers. The principal fragmentations involve the initial loss of NH3 (leading to a stabilized ion), of NH2· (probably from the hydrazone form), and of N2H2.(Journal Translation)

Spectrométrie de masse du chloro-1 diméthoxy-2,6 naphtalène; comparaison de données théoriques et expérimentales

1983 ◽  
Vol 61 (9) ◽  
pp. 2089-2091 ◽  
Author(s):  
Jean-Claude Richer ◽  
Simone Odiot
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Electron Impact Mass Spectrum ◽  
Relative Stabilities ◽  
Spectrométrie De Masse ◽  
Electron Impact Mass ◽  
Impact Mass

In an unambiguous manner we have synthesized 1-chloro-2,6-dimethoxy-d3-naphthalene (5) and examined its electron impact mass spectrum. We report here calculations on the relative stabilities of 1-chloro and 5-chloro-6-methoxy-2-naphthols (4a and 4b) and on the relative stabilities of the O—CH3 bond in the 2 and 6 positions of compound 5. [Journal translation]

The Fragment Ion C13H9O2 m/z 197 in the Mass Spectra of 2-(2′-R-phenyl)benzoic Acids

1990 ◽  
Vol 43 (1) ◽  
pp. 203 ◽  
Author(s):  
RG Gillis ◽  
QN Porter
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Electron Impact Mass Spectrum ◽  
Benzoic Acids ◽  
Ipso Substitution ◽  
Methane Chemical Ionization ◽  
Electron Impact Mass ◽  
Impact Mass

In the electron impact mass spectrum of 2-(2°-R-phenyl)benzoic acids where R=H, NO2, OCH3, COOH, or Br, an abundant fragment ion m/z 197 is formed by an ipso substitution in which R is expelled as a radical. The structure of the ion m/z 197 has been shown by collision-activated dissociation to be identical with that of the protonated molecule formed by methane chemical ionization of 6H-dibenzo[ b,d ]pyran-6-one.

Oxygen equilibration in the mass spectra of 2-benzoylbenzoic acid

1976 ◽  
Vol 29 (2) ◽  
pp. 301
Author(s):  
MJ Lacey ◽  
JS Shannon
Keyword(s):  
Mass Spectrum ◽  
Benzoic Acid ◽  
Electron Impact ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Molecular Ions ◽  
Electron Impact Mass Spectrum ◽  
Primary Fragmentation ◽  
Electron Impact Mass ◽  
Impact Mass

Positional integrity of the label is maintained in the molecular ions of 2-ben~oyl[18O]benzoic acid prior to a number of primary fragmentation modes. Positional integrity is also evident for some source and metastable reactions of the protonated molecular ions formed in its chemical ionization (H2) mass spectrum. The (M-Ph)+ ions formed in the electron impact mass spectrum, however, fragment further after complete equilibration of their oxygen atoms.

Mass Spectrometric Studies of the Ionization and Thermal Decomposition of Tungsten π-Cyclopentadienyl Tricarbonyl Dimer

1975 ◽  
Vol 53 (5) ◽  
pp. 628-632 ◽  
Author(s):  
J. R. Krause ◽  
D. R. Bidinosti
Keyword(s):  
Thermal Decomposition ◽  
High Temperature ◽  
Mass Spectrum ◽  
Temperature Dependence ◽  
Electron Impact ◽  
Enthalpy Change ◽  
Mass Spectrometric ◽  
Molecular Flow ◽  
Electron Impact Mass ◽  
Impact Mass

The ionization and thermal decomposition of tungsten π-cyclopentadienyl tricarbonyl dimer [WC5H5(CO)3]2 was investigated using a mass spectrometer fitted with single and double cell molecular flow inlet systems.The electron impact mass spectrum and appearance potentials for the principle ions in the spectrum have been measured and recorded.The enthalpy change for the dissociation[Formula: see text]obtained from van't Hoff plots of the temperature dependence of the equilibrium constant was found to be 234.4 ± 3.8 kJ/mol. This result was substantiated by an electron impact value of 221.0 ± 20.1 kJ/mol based on an ionization potential for ·WC5H5(CO)3 of 7.66 ± 0.05 eV measured in the high temperature studies.

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