Fluorination of sulfur-containing amino acids: Reaction of xenon difluoride with cysteine derivatives

1990 ◽  
Vol 68 (3) ◽  
pp. 477-479 ◽  
Author(s):  
Xiaoling Huang ◽  
Barry J. Blackburn ◽  
Steve C. F. Au-Yeung ◽  
Alexander F. Janzen
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Methyl Ester ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Xenon Difluoride ◽  
Nitrophenyl Ester ◽  
Sulfur Containing

The reaction of XeF2 with cysteine derivatives RSCH2CH(NHR)COOR, i.e., S-benzyl-N-trifluoroacetyl-L-cysteine methyl ester, S-benzyl-N-carbobenzoxy-L-cysteine p-nitrophenyl ester, and S-methyl-N-trifluoroacetyl-L-cysteine methyl ester is described. The fluorinated products PhCHFSCH2CH(NHR)COOR, PhCH2SCHFCH(NHR)COOR, and FCH2SCH2CH(NHR)COOR were identified by 1H and 19F nuclear magnetic resonance spectroscopy. PhCH2SCHFCH(NHR)COOR loses HF within 24 hours to give Z- and E-PhCH2SCH=C(NHR)COOR. If the reaction with XeF2 is carried out in the presence of moisture the sulfoxide RS(O)CH2CH(NHR)COOR and sulfone RSO2CH2CH(NHR)COOR are produced. Keywords: fluorination, XeF2, amino acids, cysteine.

scholarly journals Trafficking of Amino Acids between Neurons and Glia In Vivo. Effects of Inhibition of Glial Metabolism by Fluoroacetate

1997 ◽  
Vol 17 (11) ◽  
pp. 1230-1238 ◽  
Author(s):  
Bjørnar Hassel ◽  
Herman Bachelard ◽  
Paula Jones ◽  
Frode Fonnum ◽  
Ursula Sonnewald
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Resonance Spectroscopy ◽  
Acid Cycle ◽  
Transmitter Glutamate

Glial-neuronal interchange of amino acids was studied by 13C nuclear magnetic resonance spectroscopy of brain extracts from fluoroacetate-treated mice that received [1,2-13C]acetate and [1-13C]glucose simultaneously. [13C]Acetate was found to be a specific marker for glial metabolism even with the large doses necessary for nuclear magnetic resonance spectroscopy. Fluoroacetate, 100 mg/kg, blocked the glial, but not the neuronal tricarboxylic acid cycles as seen from the 13C labeling of glutamine, glutamate, and γ-aminobutyric acid. Glutamine, but not citrate, was the only glial metabolite that could account for the transfer of 13C from glia to neurons. Massive glial uptake of transmitter glutamate was indicated by the labeling of glutamine from [1-13C]glucose in fluoroacetate-treated mice. The C-3/C-4 enrichment ratio, which indicates the degree of cycling of label, was higher in glutamine than in glutamate in the presence of fluoroacetate, suggesting that transmitter glutamate (which was converted to glutamine after release) is associated with a tricarboxylic acid cycle that turns more rapidly than the overall cerebral tricarboxylic acid cycle.

scholarly journals An octadecatrienoic acid from Lamium purpureum L. seed oil containing 5,6-allenic and trans-16-olefinic unsaturation

1967 ◽  
Vol 105 (3) ◽  
pp. 1245-1249 ◽  
Author(s):  
K. L. Mikolajczak ◽  
Mary F. Rogers ◽  
C. R. Smith ◽  
I. A. Wolff
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Methyl Ester ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Seed Oil ◽  
Trienoic Acid ◽  
Resonance Spectroscopy ◽  
Partial Reduction

1. Lamium purpureum L. (Labiatae) seed oil contains 16% of a new acid characterized as (−)-octadeca-5,6-trans-16-trienoic acid (proposed trivial name ‘lamenallenic acid’) (Ia). The acid was isolated as its methyl ester by countercurrent distribution by using a combination of recycle–single withdrawal techniques. Methyl lamenallenate (Ib) is strongly laevorotatory. 2. The structure was established by infrared spectroscopy, nuclear-magnetic-resonance spectroscopy, quantitative hydrogenation and oxidative cleavage data of the original acid and of hydrazine partial reduction products. 3. Other unsaturated esters identified by their cleavage products were oleate, linoleate and linolenate. 4. A very small amount (less than 1%) of methyl laballenate [(−)-methyl octadeca-5,6-dienoate] was also isolated and identified.

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