Direct Anaylsis of Oxygen-18 in Organic Compounds.

Swain, C. Gardner; Tsuchihashi, Gen-ichi; Taylor, Lisa J.

doi:10.1021/ac60203a055

Cited by 11 publications

(4 citation statements)

References 20 publications

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“…Peak heights of the fragments occurring at m/e 107, 108, and 109, and m/e 152, 153, and 154 were measured for subsequent calculations. This approach to measurement of isotopic content of molecules which have been artificially enriched has been successfully employed in the past (Swain et al, 1963).…”

Section: Methodsmentioning

confidence: 99%

Mandelate racemase from Pseudomonas putida. Absence of detectable intermolecular proton transfer accompanying racemization

Sharp¹,

Hegeman²,

Kenyon³

1977

Biochemistry

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An equimolar mixture of DL-[alpha-2H]- and DL-[alpha-13C]mandelate, when incubated with mandelate racemase (EC 5.1.2.2), shows conversion of singly labeled mandelate to unlabeled mandelate, due to solvent exchange of the alpha proton, while the level of doubly labeled mandelate remains at a constant low level. Similarly, an equimolar mixture of unlabeled and DL-[alpha-2H,alpha-13C]mandelate, when incubated with the enzyme, shows conversion of doubly labeled mandelate to singly labeled mandelate, due to solvent exchange, while the level of unlabeled mandelate remains constant at 50%. Incubation of an equimolar mixture of DL-[alpha-3H]mandelate and DL-rho-chloromandelate. These results indicate that mandelate racemase does not catalyze an intermolecular proton transfer to achieve racemization. These data are necessary, but not sufficient, results to indicate that mandelate racemase operates via a one-acceptor mechanism, in which the proton abstracted from one stereochemical face of a substrate molecule is returned to the opposite face of the same carbon of the substrate molecule.

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Section: Methodsmentioning

confidence: 99%

Mandelate racemase from Pseudomonas putida. Absence of detectable intermolecular proton transfer accompanying racemization

Sharp¹,

Hegeman²,

Kenyon³

1977

Biochemistry

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“…The concentrations of 018-labeled 1 to put into this expression were taken from values of (height»)/(height" + height» + 2) for the labeled samples from which were subtracted the (small) value of this term obtained for unlabeled l. 21 For each run (two runs with 6 and 8 significant points, respectively), separate rate constants were determined with a least-squares computer program using the data from the two sets of mass spectral peaks.…”

Section: Methodsmentioning

confidence: 99%

The Structure of the Cyclopropylmethyl Carbonium Ion

Richey¹,

Richey²

1966

J. Am. Chem. Soc.

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“…A carbon rod in sodium thiosulfate served as the reference electrode. Swain, Tsuchihashi, and Taylor (307) determined radioactive oxygen content directly in organic compounds by repeated scanning of molecular weight regions of mass spectra and measurement of peak intensities.…”

Section: Cannelongo Andmentioning

confidence: 99%