by Keyword: Atp

López-Soldado I, Guinovart JJ, Duran J, (2022). Hepatic overexpression of protein targeting to glycogen attenuates obesity and improves hyperglycemia in db/db mice Frontiers In Endocrinology 13, 969924

Increased liver glycogen content has been shown to reduce food intake, attenuate obesity, and improve glucose tolerance in a mouse model of high-fat diet (HFD)-induced obesity. Here we studied the contribution of liver glycogen to the regulation of obesity and glucose metabolism in a model of type 2 diabetes and obesity, namely the db/db mouse. To this end, we crossed db/db mice with animals overexpressing protein targeting to glycogen (PTG) in the liver to generate db/db mice with increased liver glycogen content (db/db-PTG). Hepatic PTG overexpression reduced food intake and fat weight and attenuated obesity and hyperglycemia in db/db mice. Db/db-PTG mice showed similar energy expenditure and physical activity to db/db mice. PTG overexpression reduced liver phosphoenolpyruvate carboxykinase (PEPCK) protein levels and repressed hepatic glucose production in db/db mice. Moreover, increased liver glycogen elevated hepatic ATP content in these animals. However, lipid metabolism was not modified by PTG overexpression. In conclusion, increased liver glycogen content ameliorates the diabetic and obesity phenotype in db/db mice.Copyright © 2022 López-Soldado, Guinovart and Duran.

JTD Keywords: atp, db, dyslipidemia, food intake, glucose, homeostasis, liver, metabolism, mouse, receptor, Atp, Db/db, Food intake, Food-intake, Glucose, Glycogen, Liver

López-Ortiz M, Zamora RA, Antinori ME, Remesh V, Hu C, Croce R, Van Hulst NF, Gorostiza P, (2021). Fast Photo-Chrono-Amperometry of Photosynthetic Complexes for Biosensors and Electron Transport Studies Acs Sensors 6, 581-587

© 2021 American Chemical Society. Photosynthetic reactions in plants, algae, and cyanobacteria are driven by photosystem I and photosystem II complexes, which specifically reduce or oxidize partner redox biomolecules. Photosynthetic complexes can also bind synthetic organic molecules, which inhibit their photoactivity and can be used both to study the electron transport chain and as herbicides and algicides. Thus, their development, characterization, and sensing bears fundamental and applied interest. Substantial efforts have been devoted to developing photosensors based on photosystem II to detect compounds that bind to the plastoquinone sites of this complex. In comparison, photosystem I based sensors have received less attention and could be used to identify novel substances displaying phytotoxic effects, including those obtained from natural product extracts. We have developed a robust procedure to functionalize gold electrodes with photo- and redox-active photosystem I complexes based on transparent gold and a thiolate self-assembled monolayer, and we have obtained reproducible electrochemical photoresponses. Chronoamperometric recordings have allowed us to measure photocurrents in the presence of the viologen derivative paraquat at concentrations below 100 nM under lock-in operation and a sensor dynamic range spanning six orders of magnitude up to 100 mM. We have modeled their time course to identify the main electrochemical processes and limiting steps in the electron transport chain. Our results allow us to isolate the contributions from photosystem I and the redox mediator, and evaluate photocurrent features (spectral and power dependence, fast transient kinetics) that could be used as a sensing signal to detect other inhibitors and modulators of photosystem I activity.

JTD Keywords: biosensor, herbicide, kinetic model, paraquat, photo-chrono-amperometry, photosystem i, self-assembled monolayer, transparent gold microelectrode, Biosensor, Herbicide, Kinetic model, Paraquat, Photo-chrono-amperometry, Photosystem i, Self-assembled monolayer, Transparent gold microelectrode

Esteban, O., Christ, D., Stock, D., (2013). Purification of molecular machines and nanomotors using phage-derived monoclonal antibody fragments Protein Nanotechnology - Methods in Molecular Biology (ed. Gerrard, J. A.), Humana Press (New York, USA) 996, 203-217

Molecular machines and nanomotors are sophisticated biological assemblies that convert potential energy stored either in transmembrane ion gradients or in ATP into kinetic energy. Studying these highly dynamic biological devices by X-ray crystallography is challenging, as they are difficult to produce, purify, and crystallize. Phage display technology allows us to put a handle on these molecules in the form of highly specific antibody fragments that can also stabilize conformations and allow versatile labelling for electron microscopy, immunohistochemistry, and biophysics experiments. Here, we describe a widely applicable protocol for selecting high-affinity monoclonal antibody fragments against a complex molecular machine, the A-type ATPase from T. thermophilus that allows fast and simple purification of this transmembrane rotary motor from its wild-type source. The approach can be readily extended to other integral membrane proteins and protein complexes as well as to soluble molecular machines and nanomotors.

JTD Keywords: ATP synthase, Crystallization, Domain antibodies, Electron microscopy, Labelling, Membrane proteins, Monoclonal antibody fragments, Phage display, Protein purification, X-ray crystallography