摘要:

We investigated the pressure effect on the helix‐coil transition of Ala‐rich peptides in aqueous solutions by FT‐IR spectroscopy. The population of the helix conformer increased with increasing pressure. The differences in the partial molar volume between the &agr;‐helix and random coil conformers of Ala‐rich peptides are determined from the pressure dependence of the absorbance. The partial molar volume of the helix conformer is smaller than that of the coil conformer. The present result is different from the previous study (H. Noguchi,Prog. Polym. Sci. Jpn., 1975, 8, 191–199.), which reported that the partial molar volume of the helix form of polypeptide is larger than that of the coil form. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796611

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The purpose of our study is to examine the molecular dynamics under synchrotron radiation with wavelength in far infrared region that has not yet been applied. Yamada and collaborators have succeeded in developing tabletop synchrotron light sources having 15 cm orbit radius for brilliant IR radiation named “MIRROCLE‐20”. The IR radiation from the entire electron orbit of exact circular is collected by circular mirror and quasi‐ellipsoidal mirror. The IR synchrotron light spectrum is centered at 10 &mgr;m wavelength and covers from few to 100 &mgr;m. The unique beam line is the monochromatic IR irradiation system, which was unable before due to the limited IR irradiation system. We are constructing the dispersive type monochrometer with gratings that reveals 1 to 1/2 &percent; bands monochromatic IR‐rays. Specimens are placed along 15 cm long focal plane with 30 chambers, where monochromatic IR‐rays are applied through slits with 1 mm width. We have a plan to detect chemical products due to the high flux IR irradiation with specific wavelength to the proteins in water. Molecular dynamics and enzymatic reaction under IR or FIR radiation have not yet been fully understood. Generally speaking, intramolecular vibration mode will be spread and finally transfer into thermal energy. Our research object is to clarify the relaxation process of the vibration energy and to control the chemical reactions through excitation of certain vibration mode of the target proteins with monochromatic IR rays. The structural change in the proteins will be detected by its chemical products as well as change in absorption and emission spectra. Sample in our mind is for instance Horseradish peroxidase (HRP). © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796612

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Near‐infrared laser has been used to relieve patients from various kinds of pain caused by postherpetic neuralgesia, myofascial dysfunction, surgical and traumatic wound, cancer, and rheumatoid arthritis. Clinically, He‐Ne (&lgr;=632.8 nm, 780 nm) and Ga‐Al‐As (805 ± 25 nm) lasers are used to irradiate trigger points or nerve ganglion. However the precise mechanisms of such biological actions of the laser have not yet been resolved. Since laser therapy is often effective to suppress the pain caused by hyperactive excitation of sensory neurons, interactions with laser light and neural cells are suggested. As neural excitation requires large amount of energy liberated from adenosine triphosphate (ATP), we examined the effect of 830‐nm laser irradiation on the energy metabolism of the rat central nervous system and isolated mitochondria from brain. The diode laser was applied for 15 min with irradiance of 4.8 W/cm2on a 2 mm‐diameter spot at the brain surface. Tissue ATP content of the irradiated area in the cerebral cortex was 19 &percent; higher than that of the non‐treated area (opposite side of the cortex), whereas the ADP content showed no significant difference. Irradiation at another wavelength (652 nm) had no effect on either ATP or ADP contents. The temperature of the brain tissue was increased 4.5 – 5.0 °C during the irradiation of both 830‐nm and 652‐nm laser light. Direct irradiation of the mitochondrial suspension did not show any wavelength‐dependent acceleration of respiration rate nor ATP synthesis. These results suggest that the increase in tissue ATP content did not result from the thermal effect, but from specific effect of the laser operated at 830 nm. Electrophysiological studies showed the hyperpolarization of membrane potential of isolated neurons and decrease in membrane resistance with irradiation of the laser, suggesting an activation of potassium channels. Intracellular ATP is reported to regulate some kinds of potassium channels. Possible mechanisms of laser effect on neural activity through interaction between ATP and potassium channels will be discussed. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796613

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Bacteriochlorophyll(=BChl)s‐c/d/eare known to be major pigments constructing the main light‐harvesting antennae of photosynthetic green bacteria. In this study, methyl bacteriopheophorbide‐dderivatives having a series of alkyl or alkenyl substituents at the 8‐position and their zinc complexes were synthesized, and their visible absorption spectra and self‐aggregation in a solution were examined. It was shown that the C8‐substituents conjugating with the chlorin &pgr;‐system cause red‐shifts of the Qxpeaks in their monomeric forms, but do not strongly affect the supramolecular structure of the self‐aggregates along the Qyaxis. Furthermore, 31‐epimerically pure Zn‐MBPhe‐fanalogues possessing the C8‐formyl group were also synthesized, and their spectral characteristics were compared to those of the C7‐formyl compounds. It was found that the C8‐formyl group cause drastic spectral changes both in monomeric and oligomeric forms compared to the spectra of Zn‐MBPhe‐fhaving the C7‐formyl group. For example, self‐aggregates of the former showed more red‐shifted Qypeak in 6&percent;THF‐H2O than the latter, and larger diastereomeric control in the oligomeric Qypeaks was observed for C8‐formyl derivatives than for C7‐formyl compounds. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796614

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We prepared self‐aggregative bacteriochlorin (1) by modifying naturally occurring bacteriochlorophyll‐a. These synthetic 31‐epimers were separated and the absolute configuration at the 31‐position was determined. Epimerically pure 31R‐ and 31S‐1were mildly oxidized to afford the corresponding chlorins, 31R‐ and 31S‐2, respectively. A dichloromethane solution of 31R‐ or 31S‐1was diluted with 1000 fold volume of cyclohexane to give self‐aggregation species absorbing lights at a near‐infrared region (< 910 nm). The resulting Qymaximum in 31R‐1was 860 nm and red‐shifted by 2170 cm−1from the monomeric one, whereas epimeric 31S‐1showed a less red‐shifted peak at 798 nm. In contrast, self‐aggregation of 7,8‐dehydro‐compound2showed much smaller diastereomeric control. Such visible spectra indicated that the self‐aggregates of 31R‐1gave different supramolecular structures from those of 31S‐1. Molecular modeling calculation suggested that 31R‐1self‐aggregated in the same manner as 31R‐2did to give large oligomer but 31S‐1self‐aggregated in a less‐ordered orientation than 31S‐2did. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796615

出版商:AIP    

年代:1904

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.1796616

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Biofilms formed on the submerged part of reed and stone surface contained various types of microorganisms, such as eukaryotes, heterotrophic and autotrophic bacteria. Culturable bacteria from biofilms of reed and stone surface were classified into wide range of phylogenetic groups. It was also found that light irradiation affect the mineralization activity of these biofilms. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796617

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

In the nuclear encoded small subunit ribosomal DNA (18S rDNA) of symbiotic alga ofParamecium bursaria(F36 collected in Japan) possesses three intron‐like insertions (Hoshina et al., unpubl. data, 2003). The present study confirmed these exact lengths and insertion sites by reverse transcription‐PCR. Two of them were inserted atEscherichia coli16S rRNA genic position 943 and 1512 that are frequent intron insertion positions, but another insertion position (nearly 1370) was the first finding. Their secondary structures suggested they belong to Group‐I intron; one belongs to subgroup IE, others belong to subgroup IC1. Similarity search indicated these introns are ancestral ones. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796618

出版商:AIP    

年代:1904

数据来源: AIP