Reexpansion of charged nanoparticle assemblies in concentrated electrolytes.

Electrostatic forces in solutions are highly relevant to a variety of fields, ranging from electrochemical energy storage to biology. However, their manifestation in concentrated electrolytes is not fully understood, as exemplified by counterintuitive observations of colloidal stability and long-ranged repulsions in molten salts. Highly charged biomolecules, such as DNA, respond sensitively to ions in dilute solutions.

Structure and Enzymatic Activity of an Intellectual Disability-Associated Ornithine Decarboxylase Variant, G84R.

Ornithine decarboxylase (ODC) is a rate-limiting enzyme for the synthesis of polyamines (PAs). PAs are required for proliferation, and increased ODC activity is associated with cancer and neural over-proliferation. ODC levels and activity are therefore tightly regulated, including through the ODC-specific inhibitor, antizyme AZ1.

Electrostatic Control of Shape Selection and Nanoscale Structure in Chiral Molecular Assemblies.

How molecular chirality manifests at the nano- to macroscale has been a scientific puzzle since Louis Pasteur discovered biochirality. Chiral molecules assemble into meso-shapes such as twisted and helical ribbons, helicoidal scrolls (cochleates), or möbius strips (closed twisted ribbons). Here we analyze self-assembly for a series of amphiphiles, C -K, consisting of an ionizable amino acid [lysine (K)] coupled to alkyl tails with = 12, 14, or 16 carbons.

Structural basis of binding and inhibition of ornithine decarboxylase by 1-amino-oxy-3-aminopropane.

Ornithine decarboxylase (ODC) is the rate-limiting enzyme for the synthesis of polyamines (PAs). PAs are oncometabolites that are required for proliferation, and pharmaceutical ODC inhibition is pursued for the treatment of hyperproliferative diseases, including cancer and infectious diseases. The most potent ODC inhibitor is 1-amino-oxy-3-aminopropane (APA).

Structure of an AMPK complex in an inactive, ATP-bound state.

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) regulates metabolism in response to the cellular energy states. Under energy stress, AMP stabilizes the active AMPK conformation, in which the kinase activation loop (AL) is protected from protein phosphatases, thus keeping the AL in its active, phosphorylated state. At low AMP:ATP (adenosine triphosphate) ratios, ATP inhibits AMPK by increasing AL dynamics and accessibility.

Structural basis of Fusarium myosin I inhibition by phenamacril.

Fusarium is a genus of filamentous fungi that includes species that cause devastating diseases in major staple crops, such as wheat, maize, rice, and barley, resulting in severe yield losses and mycotoxin contamination of infected grains. Phenamacril is a novel fungicide that is considered environmentally benign due to its exceptional specificity; it inhibits the ATPase activity of the sole class I myosin of only a subset of Fusarium species including the major plant pathogens F. graminearum, F.

Structures of AMP-activated protein kinase bound to novel pharmacological activators in phosphorylated, non-phosphorylated, and nucleotide-free states.

AMP-activated protein kinase (AMPK) is an attractive therapeutic target for managing metabolic diseases. A class of pharmacological activators, including Merck 991, binds the AMPK ADaM site, which forms the interaction surface between the kinase domain (KD) of the α-subunit and the carbohydrate-binding module (CBM) of the β-subunit. Here, we report the development of two new 991-derivative compounds, R734 and R739, which potently activate AMPK in a variety of cell types, including β-specific skeletal muscle cells.

Substrate-Induced Allosteric Change in the Quaternary Structure of the Spermidine N-Acetyltransferase SpeG.

The spermidine N-acetyltransferase SpeG is a dodecameric enzyme that catalyzes the transfer of an acetyl group from acetyl coenzyme A to polyamines such as spermidine and spermine. SpeG has an allosteric polyamine-binding site and acetylating polyamines regulate their intracellular concentrations. The structures of SpeG from Vibrio cholerae in complexes with polyamines and cofactor have been characterized earlier.

Basis of miscoding of the DNA adduct N2,3-ethenoguanine by human Y-family DNA polymerases.

N(2),3-Ethenoguanine (N(2),3-εG) is one of the exocyclic DNA adducts produced by endogenous processes (e.g. lipid peroxidation) and exposure to bioactivated vinyl monomers such as vinyl chloride, which is a known human carcinogen.

Elucidating chemical and morphological changes in tetrachloroauric solutions induced by X-ray photochemical reaction.

Chemical and morphological changes induced by an X-ray photochemical reaction in tetrachloroauric solutions leading to Au(3+)-to-Au(0) reduction are monitored in real time by X-ray absorption spectroscopy and X-ray small angle scattering. Prior to metal precipitation, the intermediate state, also observed by other techniques, is unambiguously determined for the first time to be the reduction of Au(3+) to Au(1+), whose kinetics is strictly of the zeroth order. The morphological changes occur simultaneously in the solutions, that is, the gold complexes rearrange and aggregate, as unequivocally observed by the correlated changes in the Au L(3) emission and small angle scattering intensities.