The Grothendieck group of a quantum projective space bundle

We compute the Grothendieck group of non-commutative analogues of projective space bundles. Our results specialize to give the Grothendieck groups of non-commutative analogues of projective spaces, and specialize to recover the Grothendieck group of a usual projective space bundle over a regular noetherian separated scheme. As an application, we develop an intersection theory for quantum ruled surfaces. S. P. Smith was supported by NSF grants DMS 9701578 and 0070560 Received: March 2006     

Preparation of 5-alkyl-3-carboxymethylrhodanines and their aldose reductase inhibitory activity.

5-Alkyl-3-carboxymethylrhodanines (2) were prepared from 5-alkylmethylidene-3-carboxymethylrhodanines (1). The exo double bond of 1 was successfully reduced with NaBH4. The 1,4-addition reaction path was confirmed on the basis of proton nuclear magnetic resonance spectrum of the product (4b) obtained from the reduction of 3 using NaBD4. Optical resolution of the tert-butyl compound (2i) was achieved upon epimerization-crystallization method using L-3-amino-epsilon-caprolactam. The alkyl compounds (2) and the optical active compounds ((+)-2i, (-)-2i) were evaluated for aldose reductase inhibitory potency.     

Preparations of 5-alkylmethylidene-3-carboxymethylrhodanine derivatives and their aldose reductase inhibitory activity

Reactions of 3-carboxymethylrhodanine (1) with aldehydes (2a-u) afforded stereoselectively the 5-mono-alkylmethylidene-3-carboxymethylrhodanines (3a-u). The configuration of the 5-monoalkylmethylidene-3-carboxymethylrhodanine (3k) were examined by X-ray structure analysis and confirmed to be Z-configuration. The stereoselective reaction path was discussed. Several 5-dialkylmethylidene-3-carboxymethylrhodanines (15a-f) and alkylamino derivatives of 3-carboxymethylrhodanines (18a-o) were also prepared. These products were evaluated for aldose reductase-inhibitory potency and half of them exhibited valuable inhibitory potency.     

Pressure-induced isomerization of retinal on bacteriorhodopsin as disclosed by fast magic angle spinning NMR

Bacteriorhodopsin (bR) is a retinal protein in purple membrane of Halobacterium salinarum, which functions as a light-driven proton pump. We have detected pressure-induced isomerization of retinal in bR by analyzing 15N cross polarization-magic angle spinning (CP-MAS) NMR spectra of [zeta-15N]Lys-labeled bR. In the 15N-NMR spectra, both all-trans and 13-cis retinal configurations have been observed in the Lys N(zeta) in protonated Schiff base at 148.0 and 155.0 ppm, respectively, at the MAS frequency of 4 kHz in the dark. When the MAS frequency was increased up to 12 kHz corresponding to the sample pressure of 63 bar, the 15N-NMR signals of [zeta-15N]Lys in Schiff base of retinal were broadened. On the other hand, other [zeta-15N]Lys did not show broadening. Subsequently, the increased signal intensity of [zeta-15N]Lys in Schiff base of 13-cis retinal at 155.0 ppm was observed when the MAS frequency was decreased from 12 to 4 kHz. These results showed that the equilibrium constant of [all-trans-bR]/[13-cis-bR] in retinal decreased by the pressure of 63 bar. It was also revealed that the structural changes induced by the pressure occurred in the vicinity of retinal. Therefore, microscopically, hydrogen-bond network around retinal would be disrupted or distorted by a constantly applied pressure. It is, therefore, clearly demonstrated that increased pressure induced by fast MAS frequencies generated isomerization of retinal from all-trans to 13-cis state in the membrane protein bR.     

Room-Temperature Alkyl-Diphenylpyrene Liquefication by Molecular Desymmetrization

Achieving the lowest phase transition temperature with minimal chemical modification in highly crystalline π-conjugated molecules is a universal problem in related research fields. This paper reports room-temperature liquefication of diphenylpyrene isomers by introducing bulky yet flexible branched alkyl chains through molecular desymmetrization. Six isomers with different symmetries depending on the positions of the phenyl groups and alkyl groups were synthesized, and three of the isomers were found to be liquids at 25 °C, a state in which they have remained for more than five years. Although it is generally believed that the lower the symmetry of a molecule, the less likely it is to crystallize, one molecule with a relatively high molecular symmetry unexpectedly did not crystallize, which was evidenced by the kinetic inhomogeneity of this amorphous material (practically stable liquid) assessed by rheological analysis.