Aggregation patterns of dye molecules can govern their photophysical properties in the solid state. The linear and bent shaped dipolar benzocoumarins showed contrasting luminescence behavior in solution and in the solid state. Single crystal structures of both compounds showed π-stacking patterns with eclipsing but opposite dipole moments when viewed orthogonal to the stacking plane. Although the bent molecules are stacked in parallel in the solid state, they behave as independent molecules owing to the unfavorable excited state resonance interaction and hence emit strong fluorescence because each dipolar molecule now is in a hydrophobic environment surrounded by other molecules. This is an unusual example where the shape-dependent stacking governs the solid-state luminescence of dyes, being suggested here as a nonresonant π-stacking system.

GfsF is a multifunctional P450 monooxygenase that catalyzes epoxidation and subsequent hydroxylation in the biosynthesis of macrolide polyketide FD-891. Here, we describe the biochemical and structural analysis of GfsF. To obtain the structural basis of a dual-function reaction, we determined the crystal structure of ligand-free GfsF, which revealed GfsF to have a predominantly hydrophobic substrate binding pocket. The docking models, in conjunction with the results of the enzymatic assay with substrate analogues and site-directed mutagenesis suggested two distinct substrate binding modes for epoxidation and hydroxylation reactions, which explained how GfsF regulates the order of two oxidative reactions. These findings provide new insights into the reaction mechanism of multifunctional P450 monooxygenases.

A concise and unified strategy for the synthesis of C1-C18 macrolactone fragments of FD-891 and FD-892 as well as their analogues is reported. The strategy includes a stereoselective vinylogous Mukaiyama aldol reaction (VMAR) using chiral silyl ketene N,O-acetal to construct C6-C7 stereocenters, an E-selective ring closing metathesis to construct a C12-C13 olefin, and stereodivergent construction of a C8-C9 epoxide.

Unified synthesis of FD-891 analogs and their structure-activity relationship are described. By using stereoselective allylation/crotylation and Evans aldol chemistry, six side-chain fragments having different length and terminus were synthesized. These fragments were coupled with a macrolactone fragment, improved synthesis of which was also developed here, to generate FD-891 and five truncated analogs. These synthetic compounds as well as three analogs obtained from fermentation of gene-disrupted Streptomyces graminofaciens mutants were tested for in vitro cytotoxic activity against HeLa cells. As a result, coexistence of the C8-C9 epoxide and side-chain terminus was found to be critical for the cytotoxic activity.

We have developed a fluorogenic NAD(P)(+) detection method using 2-acetylbenzofuran. The reaction of NAD(P)(+) with 2-acetylbenzofuran produced a fluorescent product, allowing the highly-sensitive and quick detection of NAD(P)(+). This method was successfully applied to the detection of P450 substrates in the microtiter-plate format.