Chemical binding

About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.

Role of Protein Thiols in Inhibition of Sodium-Coupled Glucose Uptake by Cisplatin in Renal Brush-Border Membrane Vesicles

Abstract: The potent anticancer drug cis -diamminedichloroplatinum (II) (cDDP) impairs glucose reabsorption by renal proximal tubular cells, which leads to glucosuria. We investigated the direct effect of cDDP (0.04–2 mM) on the Na + /glucose cotransport system in brush-border membrane (BBM) vesicles from the rabbit renal cortex. cDDP induced 1) concentration-dependent inhibition of the Na + /glucose cotransport system, by decreasing its V max value and, to a lesser extent, its affinity, and 2) platinum binding to BBM vesicles, associated with decreases in protein-bound thiols. cDDP produced weaker inhibition of the Na + /glucose cotransport system and platinum binding to BBM vesicles than did highly reactive cDDP hydrated derivatives, with similar decreases in protein-bound thiols. Treatment with diethyldithiocarbamic acid (a drug protecting against cDDP nephrotoxicity), immediately after cDDP exposure, 1) partially lifted the cDDP-induced inhibition of the Na + /glucose cotransporter, 2) reduced platinum binding to BBM vesicles, but 3) did not modify the cDDP-induced decrease in protein-bound thiols. Our findings strongly suggest that cDDP-induced inhibition of the Na + /glucose cotransport system is mainly mediated by direct chemical binding of cDDP and/or its hydrated derivatives to essential sulfhydryl groups of the transport protein and may also involve other nucleophilic groups ( e.g., the -SCH 3 group of methionines).

Light and heavy element detection in thin sections of soils with the ion microprobe mass analyzer (IMMA).

Abstract: Previous research with the scanning electron microscope (SEM)-energy dispersive X-ray analyzer (EDXRA) and the electron microprobe analyzer (EMA), showed that the detection of light elements in thin sections of soils was problematic or even impossible. Consequently initial experiments were performed with the ion microprobe mass analyzer (IMMA). These preliminary investigations were carried out on a piece of root material in soil (containing both light and heavy elements) which has a 'clayey' appearance and is known as a clayified root (Parfenova et al., 1964). The presence of heavier elements in this sample was investigated by SEM-EDXRA prior to IMMA analysis. The results with the ion microprobe mass analyzer showed that all chemical elements could be analyzed in the plant fragment. Also much higher elemental detection sensitivities were found with IMMA as compared to SEM-EDXRA and EMA. This even allowed ion imaging of trace elements. High-quality ion images of both light and heavy elements could be obtained in much shorter exposure times than with SEM-EDXRA and EMA techniques. Furthermore by analysis of fragmentation ('fingerprint') spectra additional information was obtained with respect to the chemical binding of the analyzed elements. Due to these preliminary results IMMA offers full possibilities for microchemical analysis in situ of all important elements in soil specimens. This technique considerably increases possibilities in soil micromorphology. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Bio-organic studies of insect olfaction

Abstract: Pheromones interact with binding and catabolic proteins in insect olfactory sensilla, and the activated dendritic receptors are important in the transduction of a chemical binding event into an electrical signal. Selected results will be presented in which high specific activity tritium-labeled pheromones and pheromone analogs are synthesized and used to study proteins from insect antennae which bind and degrade pheromone molecules.