A tripartite cooperative mechanism confers resistance of the protein kinase A catalytic subunit to dephosphorylation.

Phosphorylation of specific residues in the activation loops of AGC kinase group (protein kinase A, G, and C families) is required for activity of most of these kinases, including the catalytic subunit of PKA (PKAc). Although many phosphorylated AGC kinases are sensitive to phosphatase-mediated dephosphorylation, the PKAc activation loop uniquely resists dephosphorylation, rendering it "constitutively" phosphorylated in cells. Previous biophysical experiments and structural modeling have suggested that the N-terminal myristoylation signal and the C-terminal FF motif in PKAc regulate its thermal stability and catalysis.

Sustainable Polyester Elastomers from Lactones: Synthesis, Properties, and Enzymatic Hydrolyzability.

Chemically cross-linked elastomers are an important class of polymeric materials with excellent temperature and solvent resistance. However, nearly all elastomers are petroleum-derived and persist in the environment or in landfills long after they are discarded; this work strives to address these issues by demonstrating the synthesis of renewable, enzymatically hydrolyzable, and mechanically competitive polyester elastomers. The elastomers described were synthesized using a novel bis(β-lactone) cross-linker and star-shaped, hydroxyl-terminated poly(γ-methyl-ε-caprolactone).

High Morphological Order in a Nearly Precise Acid-Containing Polymer and Ionomer.

Linear polyethylenes with functional groups at precise intervals along the backbone possess a number of remarkable properties, but the current synthetic methods that produce these precise polymers are difficult to scale up beyond the laboratory setting. When evaluating alternative synthetic routes, a critical question is how precise must the polymer microstructure be to achieve the properties of interest? As a first step in answering this question, we present morphological characterization of a precise polymer-that is, an acid-containing polymer wherein the acid groups are separated by either or + 1 methylene groups. We find that the size scale and uniformity of the amorphous morphologies of the nearly precise acid-containing polymer and its sodium-neutralized ionomer are essentially indistinguishable from the precise polymers based on X-ray scattering.

Rapid Determination of Polymer Stereoregularity Using Band-Selective 2D HSQC.

We report the use of band-selective 2D HSQC NMR spectroscopy to rapidly determine the stereoregularity of polymers usually analyzed by 1D C NMR spectroscopy. This approach reduced the time required to characterize the triad stereosequences of polyacrylonitrile from about an hour to a few minutes, and can be performed with sufficient C resolution to resolve higher-order stereosequences, such as the pentads of polypropylene.

Antimitogenic effect of bitter taste receptor agonists on airway smooth muscle cells.

Airway remodeling is a hallmark feature of asthma and chronic obstructive pulmonary disease. Clinical studies and animal models have demonstrated increased airway smooth muscle (ASM) mass, and ASM thickness is correlated with severity of the disease. Current medications control inflammation and reverse airway obstruction effectively but have limited effect on remodeling.