In vivo NMR spectroscopic studies on the bioenergetic changes induced by metabolic modulators in Ehrlich ascites tumour cells.

Changes in the energy metabolism of Ehrlich ascites tumour (EAT) cells induced by treatment with 2-deoxy-D-glucose (2-DG) alone and in combination with other metabolic modulators, were studied using in vivo nuclear magnetic resonance (NMR) spectroscopy. Accumulation of 2-DG-6-phosphate (2-DG-6-P) and cellular energy status as reflected in the ratio of beta ATP to inorganic phosphate (beta-ATP/Pi) in cells could be monitored as a function of time using P-31 NMR spectroscopy. Presence of 2-DG induced a significant decrease in the levels of nucleotide triphosphates, which continued to reduce for some time even after removing 2-DG from the vicinity of cells.

The influence of Mg2+ on anion binding to sarcoplasmic reticulum membranes as detected by 35Cl-NMR.

35Cl-NMR spectroscopy has been used to study the competition between anions, including nucleotides, on skeletal muscle sarcoplasmic reticulum membranes. Different chloride binding sites can be distinguished according to their Mg2+ sensitivity. Phosphate binding is enhanced by Mg2+ whereas the anion transport inhibitor pyridoxalphosphate-6-azophenyl-2'-sulfonic acid (PPAPS) binding is not.

Studies on the anion binding selectivity of sarcoplasmic reticulum membranes by 35Cl-NMR.

Anion binding sites on the membranes of sarcoplasmic reticulum vesicles can be characterized with the aid of 35Cl-NMR. Titration experiments with a series of different anions reveal that multivalent, phosphate-like anions bind much stronger to SR vesicles than monovalent anions like halides whereas oxalate seems to have an intermediate position. The binding strength decreases with decreasing ionic radius according to the following sequence: vanadate greater than phosphate greater than sulfate much greater than iodide greater than oxalate greater than bromide greater than chloride much greater than fluoride.

Temperature dependence of anion transport in the human red blood cell.

Arrhenius plots of chloride and bromide transport yield two regions with different activation energies (Ea). Below 15 or 25 degrees C (for Cl- and Br-, respectively), Ea is about 32.5 kcal/mol; above these temperatures, about 22.

Characterization of anion binding sites of sarcoplasmic reticulum vesicles by 35Cl-NMR.

Sarcoplasmic reticulum vesicles were prepared from rabbit skeletal muscle. It could be demonstrated that the anion binding sites on this membrane can be studied by 35Cl-NMR spectroscopy. Titration of sarcoplasmic reticulum vesicles with the sulfate exchange inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) revealed specific binding of this compound to the sarcoplasmic reticulum membrane.