1. RR spectra in resonance with the red absorption bands of DMSO reductase reveal the presence of C==C stretching and Mo-S stretching vibrational bands, confirming the presence of a dithiolene chelate structure in the molybdenum cofactor. Low-frequency RR spectra show 34S shifts of bands with Mo-S stretching character in oxidized (DRox) and reduced (DRred) DR, with 720.8 nm excitation producing stronger enhancement for DRox. 2. Cyanobacteria of Microcystis species produce potent hepatotoxins (microcystins); during toxin studies, an HPLC fraction containing a peptide different from microcystins with tyrosinase inhibitory activity was found. This peptide, microviridin (1), a tetradecapeptide from M. viridis, was isolated and structurally elucidated to have a novel tricyclic structure with two ester linkages (with Ser and Thr OH groups) and an amide bond (with Lys εNH2), representing the first natural tricyclic depsipeptide. It strongly inhibits tyrosinase at 3.3×10^-6 M and is not detected in field samples due to rapid decomposition by other bacteria. 3. A new microporous neutral framework molybdenum phosphate, Mo8O12(PO4)4(HPO4)2·13H2O (1), was synthesized from MoO3, Mo, H3PO4, and H2O at 200°C. Its structure features two crystallographically independent Mo4 tetramers (edge- and corner-sharing MoO6 octahedra) linked by PO4 and HPO4 tetrahedra; water ligands on Mo can be removed to create vacant coordination sites, and dehydrated 1 has at least 35% empty internal volume as per water absorption isotherms.