Prototypic G protein-coupled receptor for the intestinotrophic factor glucagon-like peptide 2

Glucagon-like peptide 2 (GLP-2) is a 33-aa proglucagon-derived peptide produced by intestinal enteroendocrine cells. GLP-2 stimulates intestinal growth and up-regulates villus height in the small intestine, concomitant with increased crypt cell proliferation and decreased enterocyte apoptosis. Moreover, GLP-2 prevents intestinal hypoplasia resulting from total parenteral nutrition. However, the mechanism underlying these actions has remained unclear. Here we report the cloning and characterization of cDNAs encoding rat and human GLP-2 receptors (GLP-2R), a G protein-coupled receptor superfamily member expressed in the gut and closely related to the glucagon and GLP-1 receptors. The human GLP-2R gene maps to chromosome 17p13.3. Cells expressing the GLP-2R responded to GLP-2, but not GLP-1 or related peptides, with increased cAMP production (EC50 = 0.58 nM) and displayed saturable high-affinity radioligand binding (Kd = 0.57 nM), which could be displaced by synthetic rat GLP-2 (Ki = 0.06 nM). GLP-2 analogs that activated GLP-2R signal transduction in vitro displayed intestinotrophic activity in vivo. These results strongly suggest that GLP-2, like glucagon and GLP-1, exerts its actions through a distinct and specific novel receptor expressed in its principal target tissue, the gastrointestinal tract.     

Solution structure of the carboxyl terminus of a human class Mu glutathione S-transferase: NMR assignment strategies in large proteins

Strategies to obtain the NMR assignments for the HN, N, CO, Calpha and Cbeta resonance frequencies for the human class mu glutathione-S-transferase GSTM2-2 are reported. These assignments were obtained with deuterated protein using a combination of scalar and dipolar connectivities and various specific labeling schemes. The large size of this protein (55 kDa, homodimer) necessitated the development of a novel pulse sequence and specific labeling strategies. These aided in the identification of residue type and were essential components in determining sequence specific assignments. These assignments were utilized in this study to characterize the structure and dynamics of the carboxy-terminal residues in the unliganded protein. Previous crystallographic studies of this enzyme in complex with glutathione suggested that this region may be disordered, and that this disorder may be essential for catalysis. Furthermore, in the related class alpha protein extensive changes in conformation of the C terminus are observed upon ligand binding. On the basis of the results presented here, the time-averaged conformation of the carboxyl terminus of unliganded GSTM2-2 is similar to that seen in the crystal structure. NOE patterns and 1H-15N heteronuclear nuclear Overhauser enhancements suggest that this region of the enzyme does not undergo motion on a rapid time scale.     

Monitoring a Commercial Barley Store in the North of England and Comparison with a Computer Simulation of Germination

The temperature, moisture and germination variations in a commercial barley store were monitored over two seasons. Initial mean temperatures of 49 and 46°C were observed. These were higher than the safe temperatures for germination predicted by the computer simulation, but still produced maltable barley. This suggested that the model was too conservative. During cooling the air was heated and the bed dried by an average of 1.5%. This ‘dryeration’ effect helped the barley to withstand the higher temperatures. Differential fan control and off‐peak running were tested and the higher 6°C differential control was shown to reduce rewetting. However, lower and more uniform temperatures were achieved with a 2°C differential. The downward flow system was essential to avoid condensation and did not pose any other serious problems. Some of the maltsters' reservations regarding cooling below 15°C, due to concerns over secondary dormancy and reheating to steep temperatures, should be alleviated by this work. Given the range of fan control options that still need to be investigated, computer simulation of the cooling, drying and germination in storage is recommended as a lower cost option than commercial testing.     

Free energy and thermodynamical critical fieldH c (T) of a superconductor with crystalline-field-split magnetic impurities: (La/itPr)Sn3

An expression for the free energy of a superconductor containing magnetic impurities with crystalline-field-split energy levels is derived. It is used to calculate the thermodynamic critical fieldH _c (T) of(La Pr)Sn ₃ . ExperimentallyH _c (T) is determined from measurements of the heat capacity of(LaPr)Sn ₃ in the normal and superconducting states. The two results are in general agreement and demonstrate the role of the inelastic pair-breaking mechanism in this nonmagnetic ground-state system.Supported by the U.S. Energy Research and Development Administration under Contract No. ERDA E(04-3)-34 PA 227.     

Self-Fourier functions and self-Fourier operators

The concept of self-Fourier functions, i.e., functions that equal their Fourier transform, is almost always associated with specific functions, the most well known being the Gaussian and the Dirac delta comb. We show that there exists an infinite number of distinct families of these functions, and we provide an algorithm for both generating and characterizing their distinct classes. This formalism allows us to show the existence of these families of functions without actually evaluating any Fourier or other transform-type integrals, a task often challenging and frequently not even possible.     

The reduction of oxygen at a metallized membrane electrode

Metallized membrane electrodes have recently been incorporated into analytical devices for monitoring the oxygen content of atmospheres. This paper describes a simple model for this type of electrode structure and shows that it applies well to the conditions used in an analytical device. The diffusion coefficient for oxygen in PTFE is shown to be 1·1 ± 0·1 × 10^?11 m² s^?1.