J A den Hollander

13C NMR studies of in vivo kinetic rates of metabolic processes

Abstract 13 C NMR has been used to follow 13 C labeling in suspensions of yeast cells, and in perfused mouse livers. Using [1- 13 C]glucose and [6- 13 C]glucose label scrambling can be observed to occur during yeast glycolysis, both in fructose-1,6-diphosphate, and in trehalose A quantitative analysis of the scrambling patterns allows one to obtain information about the kinetics of the aldolase/TPI triangle, and of futile cycling through PFK and through Fru-1,6-P 2 ,-ase. It is shown that the scrambling of the 13 C label is different for aerobic and anaerobic glycolysis. This information can be used to study the effect of oxygen upon the kinetic rates of the TPI/aldolase part of the pathway. Gluconeogenesis has been studied in yeast, using [2- 13 C]acetate as a substrate, and in perfused mouse liver by using [3- 13 C]alanine and [2- 13 C]ethanol. The appearance of the label could be followed in aminoacids, intermediates, and in the end-product of gluconeogenesis. From the labeling patterns information is obtained about the flow of the label through the various pathways. These experiments demonstrate that 13 C NMR is a valuable technique to study the rate of metabolic processes in vivo .

Surface coil spin-echo spectra without cycling the refocusing pulse through all four phases

On montre que pour les resonances qui ont un T 2 plusieurs fois plus long que T 2 * une bobine superficielle peut etre utilisee pour les series spin-echo sans cyclage de phase

The formation of grignard compounds—V: The reaction of iodomethane with magnesium in allyl phenyl ether. A second-order cidnp spectrum

Abstract Analysis of product formation reveals that in the reaction of iodomethane and magnesium in anyl phenyl ether ethane and 1-butane are the major side products. The latter product is formed mainly by addition of methyl radicals to the terminal CH2 group of allyl phenyl ehter, followed by β-scission under extrusion of a phenoxy radical. This mechanism f is confirmed by an analysis of the CIDNP spectra during the reaction; CH3 radicals escaping from CH 3 CH 3 pairs and adding to allyl phenyl ether give rise to a very clear example of a second order CIDNP spectrum in the product 1-butane, while polarization in CH 3 C 6 H 5 O-CH-CHCH 2 pairs, formed after α-H abstraction from allyl phenyl ether, leads to net effects in the products ethane (E) and 1-methylallyl phenyl ether (A).