Re-examination of the Limitations of Nitrogen-15 Isotope Dilution Technique for the Field Measurement of Dinitrogen Fixation

2015 ◽  
pp. 23-41 ◽  
Author(s):  
P. B. Vose ◽  
R. L. Victoria
Keyword(s):  
Isotope Dilution ◽  
Field Measurement ◽  
Dinitrogen Fixation ◽  
Dilution Technique ◽  
Isotope Dilution Technique

scholarly journals Beta-carotene–vitamin A equivalence in Chinese adults assessed by an isotope dilution technique – CORRIGENDUM

2013 ◽  
Vol 111 (1) ◽  
pp. 191-191
Author(s):  
Z. Wang ◽  
S. Yin ◽  
X. Zhao ◽  
R. M. Russell ◽  
G. Tang
Keyword(s):  
Vitamin A ◽  
Isotope Dilution ◽  
Beta Carotene ◽  
Dilution Technique ◽  
Chinese Adults ◽  
Isotope Dilution Technique

O-Methylierung von Adrenalin, 3.4-Dihydroxybenzoesäure und 6.7-Dihydroxycumarin in Sproßpilzen /O-Methylation of Epinephrine, 3,4-Dihydroxybenzoic Acid and 6,7-Dihydroxycoumarin in Yeasts

1976 ◽  
Vol 31 (9-10) ◽  
pp. 509-513 ◽  
Author(s):  
D Müller-Enoch ◽  
H Thomas ◽  
W Streng ◽  
W Ildfeuer ◽  
O Haferkamp
Keyword(s):  
Enzyme Activity ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Isotope Dilution ◽  
Dihydroxybenzoic Acid ◽  
Dilution Technique ◽  
Isotope Dilution Technique ◽  
Methyl Derivatives ◽  
Layer Chromatography ◽  
Methoxybenzoic Acid

Abstract In the yeasts C. albicans, C. tropicalis, and C. stellatoidea but not in C. krusei, R. rubra, and S. cerevisiae enzyme activity was found by which - as by the catechol-O-methyltransferase (EC 2.1.1.6) found in the liver - the O-methylation of epinephrine to metanephrine and paranephrine, of 3,4-dihydroxybenzoic acid to 4-hydroxy-3-methoxybenzoic acid and 3-hydroxy-4-methoxybenzoic acid, and of 6,7-dihydroxycoumarin to 7-hydroxy-6-methoxycoumarin and 6-hydroxy-7-methoxy-coumarin is catalysed. When the substrates 3,4-dihydroxybenzoic acid, or 6,7-dihydroxycoumarin or epinephrine were incubated in the presence of S-adenosyl-ʟ-[methyl-14C] methionine and S-adenosylmethionine hydrogensulfate with a 100 000 X g supernatant of C. albicans, C. tropicalis or C. stellatoidea the cor­responding O-methylethers were detected in the extracts of the incubation medium by thin-layer chromatography. Final identification of the isomeric radioactive O-methylethers obtained from 3,4-dihydroxy­ benzoic acid and 6,7-dihydroxycoumarin was performed after thin-layer chromatographic separation by the reversed isotope dilution technique. The radioactive m-and p-O-methyl derivatives from epinephrine were separated by thin-layer chromatography and then cleaved with periodate to the corresponding aldehydes which were also identified mainly by the reversed isotope dilution technique.

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