We demonstrate that a series of C3-symmetric systems with different pi-conjugated cores and three 4,4'-dicarboxy-o-terphenyl moieties（Tp, T12, T18, and Ex）form hydrogen-bonded hexagonal networks（H-HexNets）with dual or triple pores and that the H-HexNets stack without catenation to yield a low density layered assembly of H-HexNet（LA-H-HexNet）with accessible volumes up to 59％. Their crystal structures were precisely determined by single crystal X-ray analysis. Specifically, LA-H-HexNets of Tp and T12 after activation have LA-H-HexNet structures different from that of the as-formed and retain permanent porosity. A LA-H-HexNet is also demonstrated to work as a platform to achieve very unique alignment of C60. We believe that the present design principle can create a pathway to the development of a new class of highly porous functional materials.
Several enzymes containing glutamate dehydrogenase from hyperthermophiles have been reported to be expressed as inactive forms in a mesophile Escherichia coli. We have recently found that the recombinant Pyrobaculum islandicum glutamate dehydrogenase（Pis-GDH）expressed in E. coli hardly exhibits the activity, and that the heat treatment dramatically activated the inactive enzyme to the activity level comparable to that of the native enzyme. This review focuses mainly on the structural changes of the Pis-GDH in heat activation measured by small-angle X-ray scattering, differential scanning calorimetry, circular dichroism, and fluorescence spectrum in the presence of 8-anilinonaphthalene-1-sulfonate. In addition, we describe the hyperthermophilic homoserine dehydrogenase showing unique coenzyme preference as other type of the inactive recombinant enzyme. This may be informative for the better production of active recombinant enzymes from hyperthermophiles.
The morbidity of periodontal disease is reported to be 50% above in population worldwide. Some Non-Fermenting Gram-Negative Rods (NFGNR), such as Porphyromonas gingivalis, may cause periodontal disease. NFGNR is well known for utilizing peptides or proteins as energy and carbon sources instead of carbohydrates. DPPs(Dipeptidyl aminopeptidase) are peptide degradation enzymes that play a key part in the absorption of peptides. Bacterial DPPs are divided into two families(Clan SC S9, Clan PA S46). Interestingly, DPPs of Clan PA S46 are only found in bacteria. Our crystallographic studies of Pseudoxanthomonas mexicana WO24 DAP BII and P. gingivalis DPP11 revealed the catalytic and substrate recognition mechanisms of the S46 peptidases.