Koji Nishikawa

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gamma-Aminobutyric acid type A (GABA(A)) receptors are an important target for general anesthetics in the central nervous system. Site-directed mutagenesis techniques have identified amino acid residues that are important for the positive modulation of GABA(A) receptors by general anesthetics. In the present study, we investigate the role of an amino acid(More)
A method predicting protein secondary structure from sequence information could be assessed for its real efficiency by applying it to a number of proteins which lie completely outside a given data set. This type of test is performed for the three methods of Chou and Fasman (Adv. Enzymol. 47 (1978) 45-148), Robson and co-workers (J. Mol. Biol. 120 (1978)(More)
Nitrophorins are proteins occurring in the saliva of the blood-sucking insect Rhodnius prolixus to carry NO as a vasodilator and blood-coagulation inhibitor into the victim's tissue. It was suggested that the rate of NO release can be enhanced by the blood-plasma component L-cysteine [J.M.C.Ribeiro, Insect Biochem. Mol. Biol. 26 (1996) 899-905]. However,(More)
The enzyme hydrogenase reversibly converts dihydrogen to protons and electrons at a metal catalyst. The location of the abundant hydrogens is of key importance for understanding structure and function of the protein. However, in protein X-ray crystallography the detection of hydrogen atoms is one of the major problems, since they display only weak(More)
In the course of our screening for a new anti-tumor substance, the bisabolane sesquiterpenoid endoperoxide, 3,6-epidioxy-1,10-bisaboladiene (EDBD), was isolated from the edible wild-plant, Cacalia delphiniifolia. EDBD showed cytotoxicity toward human chronic myelogenous leukemia K562 and human prostate carcinoma LNCaP cell lines with IC50 values of 9.1(More)
We have designed a new curved laryngoscope blade based on a new concept of reversing the peardrop phenomenon to facilitate a view of the larynx sufficient for intubation in a greater variety of patients than the current Macintosh blade affords. The new design has a bifid tip and S-shaped spatula to exert more effective pressure in the vallecula area,(More)
Hydrogenase is a key enzyme for a coming hydrogen energy society, because it has strong catalytic activities on both uptake and production of dihydrogen. We, however, have to overcome the sensitivity against O2 of the enzyme, because hydrogenase is, generally, easily inactivated in the presence of O2. In this study, we have revisited the crystal structures(More)
Previously, the Ni-SIr state of [NiFe] hydrogenase was found to convert to the Ni-SIa state by light irradiation. Herein, large activation energies and a large kinetic isotope effect were obtained for the reconversion of the Ni-SIa state to the Ni-SIr state after the Ni-SIr-to-Ni-SIa photoactivation, suggesting that the Ni-SIa state reacts with H2O and(More)