The helices present in 17 beta-HSD that were not in the two previous short-chain dehydrogenase structures are located at one end of the substrate-binding cleft away from the catalytic triad. These helices restrict access to the active site and appear to influence substrate specificity. Modeling the position of estradiol in the active site suggests that a histidine side chain may play a critical role in substrate recognition. One or more of these helices may also be involved in the reported association of the enzyme with membranes. A model for steroid and cofactor binding as well as for the estrone to estradiol transition state is proposed. The structure of the active site provides a rational basis for designing more specific inhibitors of this breast cancer associated enzyme.

Dethiobiotin synthetase (DTBS ; E.C. 6.6.6.6), the penultimate enzyme in the biosynthesis of the essential vitamin biotin, is a new potential target for novel herbicides. Inhibitors were designed based on mechanistic and structural information. The in-vitro activities of these potential inhibitors versus the bacterial enzyme are reported here. Mimics of 7,8-diaminopelargonic acid (DAPA) or the DAPA carbamate reaction intermediate were substrates or partial substrates for the enzyme. Synergistic binding with ATP was noted with compounds which contained an amino functionality. NMR studies and X-ray structures conürmed that the inhibitors could be phosphorylated by the enzyme. Several series of potential inhibitors were designed to take advantage of this partial substrate activity by generating potentially more tightly bound phosphorylated inhibitors in situ. Structure-activity relationships for these series based on both substrate and inhibitory activity are described herein. An X-ray structure for one of these inhibitors is also discussed. Although considerable potential for inhibitors of this type was demonstrated, none of the compounds reported showed sufficient herbicidal activity to be a commercial proposition.

: Dethiobiotin synthetase (DTBS ; E.C. 6.6.6.6), the penultimate enzyme in the biosynthesis of the essential vitamin biotin, is a new potential target for novel herbicides. Inhibitors were designed based on mechanistic and structural information. The in-vitro activities of these potential inhibitors versus the bacterial enzyme are reported here. Mimics of 7,8-diaminopelargonic acid (DAPA) or the DAPA carbamate reaction intermediate were substrates or partial substrates for the enzyme. Synergistic binding with ATP was noted with compounds which contained an amino functionality. NMR studies and X-ray structures conürmed that the inhibitors could be phosphorylated by the enzyme. Several series of potential inhibitors were designed to take advantage of this partial substrate activity by generating potentially more tightly bound phosphorylated inhibitors in situ. Structure-activity relationships for these series based on both substrate and inhibitory activity are described herein. An X-ray structure for one of these inhibitors is also discussed. Although considerable potential for inhibitors of this type was demonstrated, none of the compounds reported showed sufficient herbicidal activity to be a commercial proposition.

C401In-situ diffraction experiments were performed on SOFC under standard operating conditions, more specifically during successive cycles of reduction and reoxidation at ~ 850 °C.The experiment was performed with the spiral slit set-up at beamline ID15 at the ESRF and an X-ray wavelength of = 0.173 Å.The strain distribution within the three constituent layers of the SOFC was determined from the distortion of the monitored DebyeScherrer-rings. Dilithium phthalocyanine is a compound that shows promise as the dielectric for lithium-lithium ion batteries. The compound forms small, flakey crystals from the few solvents in which it can be dissolved. Experimental evidence indicates that the lithium atoms within the solid structure migrate in the presence of an electric field. The determination of the crystal and molecular structure was initiated so as to determine the pathways through which the lithium ions move. Iron cobaltites show the ferrimagnetism to have a spinel structure, where Co and Fe ions occupy tetrahedral A and octahedral B sites in various valence states. Therefore, the determination of cation distribution between the two kinds of sites is indispensable to the interpretation of the magnetic properties of cobaltites.Fortunately, we succeeded to synthesize single crystals of Fe 1+x Co 2-x O 4 (x = 0.2) by the hydrothermal reaction. The site occupancy of Fe and Co ions was first determined by the singlecrystal synchrotron X-ray diffraction method, where the anomalous scattering effect was used at the Co K absorption edge ( = 1.6182 Å) in the BL-10A station of the Photon Factory. Then, the electronic information from X-ray absorption near edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) spectra was utilized for determining the valence states of Fe and Co ions. The absorption experiments were performed at both Fe K and Co K edges at BL-3A.It was found that all Fe ions exist as trivalent ions in Fe K XANES spectra, while the valences of Co ions were uniquely obtained from the intensity variation of XMCD signals in the solid solutions [1].Based on the full determination for x = 0.2 sample, the most plausible chemical formula and magnetic structures have been suggested through the solid solution of Fe 1+x Co 2-x O 4 (0 x 1).[1] Kita N., Shibuichi N, Sasaki S., J. Synchrotron Rad., 2001, 8 The phase Sr 7 Zr 4 Nb 6 O 30 in the SrO-ZrO 2 -NbO 2.5 system was recently discovered in our laboratories. X-ray diffraction patterns have shown that the compound Sr 7 Zr 4 Nb 6 O 30 forms a cubic perovskite substructure with an additional modulation (satellite reflections at ½<111> p ). This compound is analogous to the perovskite Sr x NbO 3 , 0.7 x 1, which exists over a significant range of composition [1]. In contrast to our new phase Sr x NbO 3 , 0.7 x 1, does not display additional ordering (no satellite reflections were found despite intensive searching). Therefore it is likely that the additional reflections for our new phase are due to Nb/Zr ordering.If x in the Sr x NbO 3 solid solution equals 1 a...