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Effect of Asp193 on Proton Affinity of the Schiff Base in pharaonis phoborhodopsin
Iwamoto, Masayuki,Furutani, Yuji,Sudo, Yuki,Shimono, Kazumi,Kandori, Hideki,Kamo, Naoki Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
Spectroscopic titration of D 193N and D 193E mutants of pharaonis phoborhodopsin (ppR) were performed to evaluate the pK$_{a}$ of the Schiff base Asp 193 corresponds to Glu204 of bacteriorhodopsin (bR). The pK$_{a}$ of the Schiff base (SBH$^{+}$) of D193N was 10.1~10.0 (at XH$^{+}$) and 11.4~11.6 (at X) depending on the protonation state of a certain residue (designated by X) and independent on CI$^{[-10]}$ , while those of the wild-type and D193E were> 12. pK$_{a}$ of XH$^{+}$ were; 11.8~11.2 at the state of SB, 10.5 at SBH$^{+}$ state in the presence of CI$^{[-10]}$ , and 9.6 at SBH$^{+}$ without CI$^{[-10]}$ These imply the presence of a long-range interaction in the extracellular channel.r channel.
Low-Temperature FTIR Spectroscopy of Bacteriorhodopsin and Phoborhodopsin
Kandori, Hideki,Furutani, Yuji,Shimono, Kazumi,Iwamoto, Masayuki,Sudo, Yuki,Shichida, Yoshinori,Kamo, Naoki Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
Archaeal rhodopsins possess retinal molecule as their chromophores, and their light-energy and light-signal conversions are triggered by all-trans to 13-cis isomerization of the retinal chromophore. Relaxation through structural changes of protein then leads to functional processes, proton pump in bacteriorhodopsin (bR) and transducer activation in phoborhodopsin (pR). It is known that sensory rhodopsins can pump protons in the absence of their transducers. Thus, there should be common and specific features in their protein structural changes for function. In this paper, our r ecent studies on pR from Natronobacterium pharaonis (ppR) by means of low-temperature Fourier-transform infrared (FTIR) spectroscopy are compared with those of bR. In particular, protein structural changes upon retinal photoisomerization are studied. Comparative investigation of ppR and bR revealed the similar structures of the polyene chain of the chromophore and water-containing hydrogen-bonding network, whereas the structural changes upon photoisomerization were more extended in ppR than in bR. Extended protein structural changes were clearly shown by the assignment of the C=O stretch of Asnl05. FTIR studies of a ppR mutant with the same retinal binding site as in bR revealed that the Schiff base region is important to determine their colors.
Jung, J.,Furutani, H.,Uematsu, M.,Kim, S.,Yoon, S. Copernicus GmbH 2013 Atmospheric Chemistry and Physics Vol.13 No.1
<P>Abstract. Aerosol, rainwater, and sea fog water samples were collected during the cruise conducted over the subarctic western North Pacific Ocean in the summer of 2008, in order to estimate dry, wet, and sea fog deposition fluxes of atmospheric inorganic nitrogen (N). During sea fog events, mean number densities of particles with diameters larger than 0.5 μm decreased by 12-78%, suggesting that particles with diameters larger than 0.5 μm could act preferentially as condensation nuclei (CN) for sea fog droplets. Mean concentrations of nitrate (NO3−), methanesulfonic acid (MSA), and non sea-salt sulfate (nss-SO42−) in sea fog water were higher than those in rainwater, whereas those of ammonium (NH4+) in both sea fog water and rainwater were similar. These results reveal that sea fog scavenged NO3− and biogenic sulfur species more efficiently than rain. Mean dry, wet, and sea fog deposition fluxes for atmospheric total inorganic N (TIN; i.e. NH4+ + NO3−) over the subarctic western North Pacific Ocean were estimated to be 4.9 μmol m−2 d−1, 33 μmol m−2 d−1, and 7.8 μmol m−2 d−1, respectively. While NO3− was the dominant inorganic N species in dry and sea fog deposition, inorganic N supplied to surface waters by wet deposition was predominantly by NH4+. The contribution of dry, wet, and sea fog deposition to total deposition flux for TIN (46 μmol m−2 d−1) were 11%, 72%, and 17%, respectively, suggesting that ignoring sea fog deposition would lead to underestimate of the total influx of atmospheric inorganic N into the subarctic western North Pacific Ocean, especially in summer periods. </P>
Jung, J.,Furutani, H.,Uematsu, M.,Park, J. Pergamon Press ; Elsevier [distribution] 2014 Atmospheric environment Vol.99 No.-
Atmospheric concentrations of non-sea-salt sulfate (nss-SO<SUB>4</SUB><SUP>2-</SUP>) and methanesulfonic acid (MSA) were measured over the Pacific Ocean between 48<SUP>o</SUP>N and 55<SUP>o</SUP>S during the KH-08-2 and MR08-06 cruises in summers of 2008 and 2009, in order to investigate spatial distributions of each species and MSA/nss-SO<SUB>4</SUB><SUP>2-</SUP> ratio. In the subarctic western North Pacific, mean concentrations of nss-SO<SUB>4</SUB><SUP>2-</SUP> and MSA in bulk (fine + coarse) aerosols were 1.1 μg m<SUP>-3</SUP> and 0.061 μg m<SUP>-3</SUP>, whereas those in the South Pacific were 0.25 μg m<SUP>-3</SUP> and 0.043 μg m<SUP>-3</SUP>, respectively. In the subtropical western North Pacific, it was observed that nss-SO<SUB>4</SUB><SUP>2-</SUP> concentration sharply increased from 0.45 μg m<SUP>-3</SUP> up to 4.2 μg m<SUP>-3</SUP> under the dominant influence of the Kilauea volcano, while that of MSA remained low. Mean MSA/nss-SO<SUB>4</SUB><SUP>2-</SUP> ratio observed in the South Pacific was approximately 3.7 times higher than that in the subarctic western North Pacific, although the mean MSA concentration in the subarctic western North Pacific was a factor of 1.4 higher than that in the South Pacific. The distributions of nss-SO<SUB>4</SUB><SUP>2-</SUP>, MSA, and MSA/nss-SO<SUB>4</SUB><SUP>2-</SUP> ratio suggested that aerosol nss-SO<SUB>4</SUB><SUP>2-</SUP> plays a key role in the latitudinal variation in MSA/nss-SO<SUB>4</SUB><SUP>2-</SUP> ratio over the North and South Pacific during summer periods, and that high MSA concentrations in the subarctic western North Pacific and the South Pacific were related to high biological productivity and low air temperature. During the cruises, an inverse relationship (r = -0.72, p < 0.01) was observed between satellite-derived chlorophyll a concentration and air temperature, showing that high biological productivity occurred at high latitudes, where air temperature were relatively low, in both hemispheres during the summer periods. Although both MSA concentration and MSA/nss-SO<SUB>4</SUB><SUP>2-</SUP> ratio showed inverse and positive relationships with air temperature and chlorophyll a concentration, respectively, the correlations between these variables were weak, suggesting that the distributions of MSA concentration and MSA/nss-SO<SUB>4</SUB><SUP>2-</SUP> ratio over the North and South Pacific during the summer periods were influenced by more complex factors. Estimates using the MSA/nss-SO<SUB>4</SUB><SUP>2-</SUP> ratios measured in different latitude regions in the Pacific Ocean indicated that the contributions from biogenic sources accounted for 9.6-58% of the total nss-SO<SUB>4</SUB><SUP>2-</SUP> in aerosols collected in the subarctic western North Pacific, 15-85% in the subtropical western North Pacific, 10-70% in the central North Pacific, and 12-97% in the South Pacific, showing strong influence of anthropogenic nss-SO<SUB>4</SUB><SUP>2-</SUP> in the subarctic western North Pacific despite the higher mean concentration of MSA in the subarctic western North Pacific than in the South Pacific.
An Inward Proton Transport Using Anabaena Sensory Rhodopsin
Akira Kawanabe,Yuji Furutani,정광환,Hideki Kandori 한국미생물학회 2011 The journal of microbiology Vol.49 No.1
ATP is synthesized by an enzyme that utilizes proton motive force and thus nature creates various proton pumps. The best understood proton pump is bacteriorhodopsin (BR), an outward-directed light-driven proton pump in Halobacterium salinarum. Many archaeal and eubacterial rhodopsins are now known to show similar proton transport activity. Proton pumps must have a specific mechanism to exclude transport in the reverse direction to maintain a proton gradient, and in the case of BR, a highly hydrophobic cytoplasmic domain may constitute such machinery. Although an inward proton pump has neither been created naturally nor artificially, we recently reported that an inward-directed proton transport can be engineered from a bacterial rhodopsin by a single amino acid replacement. Anabaena sensory rhodopsin (ASR) is a photochromic sensor in freshwater cyanobacteria, possessing little proton transport activity. When we replace Asp217at the cytoplasmic domain (distance ~15 Å from the retinal chromophore) to Glu, ASR is converted into an inward proton transport, driven by absorption of a single photon. FTIR spectra clearly show an increased proton affinity for Glu217, which presumably controls the unusual directionality opposite to normal proton pumps.