The AMP-activated protein kinase (AMPK) is an alphabetagamma heterotrimer that plays a pivotal role in regulating cellular and whole-body metabolism. Activation of AMPK reverses many of the metabolic defects associated with obesity and type 2 diabetes, and therefore AMPK is considered a promising target for drugs to treat these diseases. Recently, the thienopyridone A769662 has been reported to directly activate AMPK by an unexpected mechanism. Here we show that A769662 activates AMPK by a mechanism involving the beta subunit carbohydrate-binding module and residues from the gamma subunit but not the AMP-binding sites. Furthermore, A769662 exclusively activates AMPK heterotrimers containing the beta1 subunit. Our findings highlight the regulatory role played by the beta subunit in modulating AMPK activity and the possibility of developing isoform specific therapeutic activators of this important metabolic regulator.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a debilitating long-term multisystem disorder with a central and inexplicably persistent fatigue symptom that is unable to be relieved by rest. Energy metabolism and oxidative stress have been recent focal points of ME/CFS research and in this study we were able to elucidate metabolic pathways that were indicative of their dysfunction. Blood and urine samples were collected from 34 females with ME/CFS (34.9 ± 1.8 SE years old) and 25 non-ME/CFS female participants (33.0 ± 1.6 SE years old). All samples underwent metabolic profiling via 1D 1 H Nuclear Magnetic Resonance spectroscopy and quantitated metabolites were assessed for significance. Blood glucose was elevated while blood lactate, urine pyruvate, and urine alanine were reduced indicating an inhibition of glycolysis that may potentially reduce the provision of adequate acetyl-CoA for the citric acid cycle. We propose that amino acids are being increasingly used to provide an adequate carbohydrate source for the citric acid cycle. We suggest that this is via glutamate forming 2-oxoglutarate through an enzyme that deaminates it and subsequently elevates blood aspartate. Dysfunctional energy metabolism appears to have impacted creatinine and its elevation in urine suggests that it may be used as an alternative for anaerobic ATP production within muscle. A decrease in blood hypoxanthine and an increase in urine allantoin further suggest the elevation of ROS in ME/CFS patients. These findings bring new information to the research of energy metabolism, chronic immune activation and oxidative stress issues within ME/CFS.

The key to obtaining the model-free description of the dynamics of a macromolecule is the optimisation of the model-free and Brownian rotational diffusion parameters using the collected R 1 , R 2 and steady-state NOE relaxation data. The problem of optimising the chi-squared value is often assumed to be trivial, however, the long chain of dependencies required for its calculation complicates the model-free chi-squared space. Convolutions are induced by the Lorentzian form of the spectral density functions, the linear recombinations of certain spectral density values to obtain the relaxation rates, the calculation of the NOE using the ratio of two of these rates, and finally the quadratic form of the chi-squared equation itself. Two major topological features of the model-free space complicate optimisation. The first is a long, shallow valley which commences at infinite correlation times and gradually approaches the minimum. The most severe convolution occurs for motions on two timescales in which the minimum is often located at the end of a long, deep, curved tunnel or multidimensional valley through the space. A large number of optimisation algorithms will be investigated and their performance compared to determine which techniques are suitable for use in model-free analysis. Local optimisation algorithms will be shown to be sufficient for minimisation not only within the model-free space but also for the minimisation of the Brownian rotational diffusion tensor. In addition the performance of the programs Modelfree and Dasha are investigated. A number of model-free optimisation failures were identified: the inability to slide along the limits, the singular matrix failure of the Levenberg-Marquardt minimisation algorithm, the low precision of both programs, and a bug in Modelfree. Significantly, the singular matrix failure of the Levenberg-Marquardt algorithm occurs when internal correlation times are undefined and is greatly amplified in model-free analysis by both the grid search and constraint algorithms. The program relax (http://www.nmr-relax.com) is also presented as a new software package designed for the analysis of macromolecular dynamics through the use of NMR relaxation data and which alleviates all of the problems inherent within model-free analysis.

Acid-sensing ion channel 1a (ASIC1a) is a primary acid sensor in the peripheral and central nervous system. It has been implicated as a novel therapeutic target for a broad range of pathophysiological conditions including pain, ischemic stroke, depression, and autoimmune diseases such as multiple sclerosis. The only known selective blocker of ASIC1a is -TRTXPc1a (PcTx1), a disulfide-rich 40-residue peptide isolated from spider venom. -TRTX-Pc1a is an effective analgesic in rodent models of acute pain and it provides neuroprotection in a mouse model of ischemic stroke. Thus, understanding the molecular basis of the -TRTX-Pc1a-ASIC1a interaction should facilitate development of therapeutically useful ASIC1a blockers. We therefore developed an efficient bacterial expression system to produce a panel of -TRTX-Pc1a mutants for probing structure-activity relationships as well as isotopically labeled toxin for determination of its solution structure and dynamics. We demonstrate that the toxin pharmacophore resides in a ␤-hairpin loop that was revealed to be mobile over a wide range of time scales using molecular dynamics simulations in combination with NMR spin relaxation and relaxation dispersion measurements. The toxin-receptor interaction was modeled by in silico docking of the toxin structure onto a homology model of rat ASIC1a in a restraints-driven approach that was designed to take account of the dynamics of the toxin pharmacophore and the consequent remodeling of side-chain conformations upon receptor binding. The resulting model reveals new insights into the mechanism of action of -TRTX-Pc1a and provides an experimentally validated template for the rational design of therapeutically useful -TRTX-Pc1a mimetics.

NMR spectroscopy is a powerful tool for studying the structure, function and dynamics of biological macromolecules. However, non‐spectroscopists often find NMR theory daunting and data interpretation nontrivial. As the first of two back‐to‐back reviews on NMR spectroscopy aimed at non‐spectroscopists, the present review first provides an introduction to the basics of macromolecular NMR spectroscopy, including a discussion of typical sample requirements and what information can be obtained from simple NMR experiments. We then review the use of NMR spectroscopy for determining the 3D structures of macromolecules and examine how to judge the quality of NMR‐derived structures.