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Applications of light-harvesting arrays range from alternative sources of energy to field of photonic and optoelectronic devices are described. It is also shown that the short-time excitation energy dynamics in coupled ring systems depends on the initial excitation process.

The mechanism of the reductive release of iron from thecavityof the iron storage protein, ferritin, has been difficult to confirmon the molecular level using experimental studies. In this paper,we use a variety of computational tools to study the binding of flavinredox agents to the protein surface, and the subsequent electron transfer(ET) through the protein coat. Flavin binding sites are identifiedthat represent efficient routes to reduction of Fe(III) across theprotein coat in human and bacterial ferritins. Using the pathwaysmodel and Dutton’s packing density model, we show that ET acrossthe protein coat to nucleation sites is feasible. Different proteinconfigurations for human heavy and light chain ferritin were obtainedalong classical molecular dynamics trajectories and used for flavinbinding and ET studies. We find that protein configuration affectsboth the binding and ET rate constants significantly. We show thatthe maximum possible ET rate constants to the nucleation site GLU-61in human heavy chain ferritin for protein configurations along a MDsimulation trajectory can differ by about 8 orders of magnitude comparedto the crystal structure and in human light-chain ferritin rate constantsvary by about 4 orders of magnitude. [ABSTRACT FROM AUTHOR]

A 6-step synthesis of the naphthoic acid component of the natural antitumor agent neocarzinostatin chromophore is described. The synthetic route employs a 4-bromo-3-methylanisole as the starting material, proceeds in 31-37% yield for the 6 steps, and features as the key step a photocyclization reaction that is an interesting variant of known photocyclization reactions of stilbenes and phenylbutadienes., Chemistry and Chemical Biology

The title compound, (4S,5S,8R, IOZ)-2,2,5,6,8,10-hexamethyl-4-phenyl- 1,3-dioxa-6-aza-2-silacycloun-dec-10-en-7-one, crystallizes with two virtually identical molecules in the asymmetric unit, each with the same absolute configuration. Bond distances and angles are normal; the closest approaches across the ring between non-bonded atoms are all greater than 3.35 .A,. The amide and enol ether groups are planar to within +- 0.06 A., Chemistry and Chemical Biology

Loss of insulin sensitivity, α- and β-cell dysfunction, and impairment in incretin effect have all been implicated in the pathophysiology of type 2 diabetes (T2D). Parsimonious mathematical models are useful in quantifying parameters related to the pathophysiology of T2D. Here, we extend the minimum model developed to describe the glucose-insulin-glucagon dynamics in the isoglycemic intravenous glucose infusion (IIGI) experiment to the oral glucose tolerance test (OGTT). The extended model describes glucose and hormone dynamics in OGTT including the contribution of the incretin hormones, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-1 (GLP-1), to insulin secretion. A new function describing glucose arrival from the gut is introduced. The model is fitted to OGTT data from eight individuals with T2D and eight weight-matched controls (CS) without diabetes to obtain parameters related to insulin sensitivity, β- and α-cell function. The parameters, i.e., measures of insulin sensitivity, a 1 , suppression of glucagon secretion, k 1 , magnitude of glucagon secretion, γ 2 , and incretin-dependent insulin secretion, γ 3 , were found to be different between CS and T2D with P values < 0.002, <0.017, <0.009, <0.004, respectively. A new rubric for estimating the incretin effect directly from modeling the OGTT is presented. The average incretin effect correlated well with the experimentally determined incretin effect with a Spearman rank test correlation coefficient of 0.67 ( P < 0.012). The average incretin effect was found to be different between CS and T2D ( P < 0.032). The developed model is shown to be effective in quantifying the factors relevant to T2D pathophysiology. NEW & NOTEWORTHY A new extended model of oral glucose tolerance test (OGTT) has been developed that includes glucagon dynamics and incretin contribution to insulin secretion. The model allows the estimation of parameters related to α- and β-cell dysfunction, insulin sensitivity, and incretin action. A new function describing the influx of glucose from the gut has been introduced. A new rubric for estimating the incretin effect directly from the OGTT experiment has been developed. The effect of glucose dose was also investigated.