摘要:

Molecular conformational equilibrium is the most central concept in the chemistry and biochemistry of chain molecules. This equilibrium is occasionally affected by environmental conditions such as temperature, pressure and solvents. Such structural flexibility of molecules plays an important role in chemical and biological phenomena in liquid phase. In particular, the equilibrium in water is of vital importance for biological systems.The pressure effect on the equilibria in liquids can give information of volume differences between trans/gauche of rotational isomers or native/unfolded states of proteins. The volume properties are important to understand the intermolecular interaction between the solute and solvent molecules and the molecular mechanism. It is accepted that the volume changes for trans/gauche equilibrium of rotational isomers in non‐polar solvents are less than −5 cm3/mol and for native /unfolded states of proteins in aqueous media less than −100 cm3/mol.Recent development of high pressure FTIR spectroscopy combined with resolution enhancement techniques and Raman spectroscopy is able to detect the signal of each rotational isomer in dilute aqueous solution and the secondary structure of the pressure induced structure changes of proteins in water. In this study, the effect of pressure on the conformational equilibrium between rotational isomers of haloacetone, alanine dipeptide, and proteins in aqueous media has been studied by the FTIR and Raman spectroscopes. On the base of both observed volume changes of simple chain molecules and proteins, the molecular mechanism on the pressure induced conformational changes will be discussed. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796581

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Synchrotron radiation X‐ray diffraction has been intensively applied to bacteriorhodopsin photointermediates to understand the molecular mechanism of light‐driven proton pump. Time‐resolved X‐ray diffraction with time resolution of 244msec revealed that the two types of the structures appear during a photocycle. In order to realize the time resolution of 5&mgr;sec, we developed a new snap shot diffraction technique. With the method, we revealed that the structural change is triggered by the deprotonation of Schiff base. Based on the structures, we proposed a conformation‐controlled conformational change model. The apparent discrepancy between crystal structures and low resolution structures is also discussed. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796582

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The history of drug‐related protein crystallography and drug design is reviewed to show that “Lead Generation” is high‐lighted in the pharmaceutical industry nowadays. A new drug design method has been developed. The method gave very high success rate; 10–60 &percent; gave < 100 &mgr;M, 90 &percent; gave < 10 mM. The crystal structures of drug‐protein complexes have become even more important to give solid experimental bases for e.g. 1,000 designed structures and to find the new mechanisms of drug action. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796583

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We have successfully observed dynamical Brownian motions in an individual DNA molecule and other biological ones in real time with one‐100th the atomic‐scale precision (picometer‐scale precision) using X‐rays of the super photon ring‐8 (SPring‐8) for the first time. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796584

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

X‐ray microscopy microscope installed at the beam line ID21 at European Synchrotron Radiation Facility (ESRF) was used for the elucidation of micro‐distribution of vanadium in ascidians. In order to examine chemical states of vanadium in the alive blood cell, a high pressure cryo‐fixation technique was applied to fix its chemical states of vanadium. We have succeeded in observing uniform distribution of vanadium in the vacuole, in identifying the valency of vanadium in the cell, and more importantly in finding granules rich in vanadium of the 4th valency. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796585

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Widely tunable coherent terahertz (THz) wave generation has been demonstrated based on the parametric oscillation using MgO doped LiNbO3crystal pumped by a Q‐switched Nd:YAG laser. This method exhibits multiple advantages like wide tunability, coherency and compactness of its system. We have developed a novel basic technology for terahertz (THz) imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral transillumination images, using absorption spectra previously measured with a widely tunable THz‐wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796586

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

MIRRORCLE‐6X, the unique portable synchrotrons, generates brilliant hard X‐rays. The purpose of this study is to investigate the biological effects of synchrotron radiation on cancer cells to identify its effectiveness. A549 human lung adenocarcinoma and DU145 human prostate adenocarcinoma cells were used. We examined biological effects on cancer cells by colony formation assay, micronucleus assay, WST‐1 method, and apoptosis detection of flow cytometry. Results of these assay revealed that the biological effects of X‐ray generated from MIRRORCLE‐6X on cancer cells are similar to those of 4 MV X‐ray from linear accelerator (linac). © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796587

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Hair samples of 37 donors including 12 patients of hepatocelluar carcinoma have been examined by fluorescent X‐ray analysis using the SPring‐8, which detected many kinds of trace elements in a single hair root. Homeostasis in concentrations of Ca, Fe, Cu, Zn and Sr was found to be in consistency with their concentrations measured for the serum in a healthy case. Unusual increases of [Cu] and/or [Fe] were observed for hair of the patients by disorder of the liver function to excrete these elements due to cancer. The unique behavior observed for [Ca] is discussed in relation to the “Calcium paradox”, a phenomenon of increasing from the regulated Ca ion concentration in cytosol, which is caused by parathyroid hormone in the case of Ca deficiency due to many kinds of disease as well as insufficient intake and absorption of Ca. It is concluded that the analysis of hair is useful for screening serious diseases such as the cancer and osteoporosis. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796588

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

In order to estimate the optimum laser conditions for efficient dissociation of cholesterol ester in an arteriosclerotic region of blood vessels, we have investigated the relationship between laser wavelength and power density on cholesterol ester dissociation using a mid infrared free electron laser (MIR‐FEL). In this study, cholesteryl oleate, which is a typical cholesterol ester found in arteriosclerotic regions, was irradiated with 5.75‐&mgr;m‐FELs, which cause vibration of ester bonds. Two results were obtained. (1) Ester dissociated depending on the absorption coefficient, and the macropulse duration was shorter than the thermal relaxation time, showing that ester bonds dissociated into carboxylic acid and cholesterol by macropulse‐induced thermal effects without accompanying thermal diffusion, (2) Using a wavelength of 5.75 &mgr;m, the maximum ester dissociation ratio was achieved under the optimum laser conditions of a macropulse energy density of 0.4–1.0 J/cm2. We conclude that MIR pulsed‐lasers with a wavelength of 5.75 &mgr;m can be useful for removal of cholesteryl ester in an arteriosclerotic region of blood vessels. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796589

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A pressure‐tuning FTIR spectroscopic technology for the investigation of the structural and dynamic properties at the molecular level in biological cells and tissues has been developed in our laboratory. This allowed us to study the molecular basis of various biomedical events including structural and dynamic changes of bio‐molecules in diseased tissues and cells. After a brief introduction of this technology and a summary of various biomedical applications of this technology, details of the biomedical applications to the study of structural changes in bio‐molecules of human tissues during the neoplastic transition and to the screening of human cervical cancer and precancerous lesions including clinical statistics are given. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796590

出版商:AIP    

年代:1904

数据来源: AIP