Nagoya Institute of Technology

About: Nagoya Institute of Technology is a education organization based out in Nagoya, Japan. It is known for research contribution in the topics: Thin film & Catalysis. The organization has 10766 authors who have published 19140 publications receiving 255696 citations. The organization is also known as: Nagoya Kōgyō Daigaku & Nitech.

Vibrational frequency and dipolar orientation of the protonated Schiff base in bacteriorhodopsin before and after photoisomerization.

Abstract: Light-driven proton transport in bacteriorhodopsin (BR) is initiated by photoisomerization of the retinylidene chromophore, which perturbs the hydrogen bonding network in the Schiff base region of the active site. This study aimed to identify the frequency and dipolar orientation of the N-D stretching vibrations of the Schiff base before and after photoisomerization, by means of low-temperature polarized FTIR spectroscopy of [zeta-(15)N]lysine-labeled BR in D(2)O. (15)N-shifted modes were found at 2123 and 2173 cm(-1) for BR, and at 2468 and 2495 cm(-1) for the K intermediate. The corresponding N-H stretches are at approximately 2800 cm(-1) for BR and 3350-3310 cm(-1) for the K intermediate. The shift to a 350 cm(-1) higher frequency upon photoisomerization is consistent with loss of the hydrogen bond of the Schiff base. The N-D stretch frequencies of the Schiff base in BR and the K intermediate are close to the O-D stretch frequencies of strongly hydrogen bonded water and Thr89, respectively. The angles of the dipole moments of the N-D stretches to the membrane normal were determined to be 60-65 degrees for BR and approximately 90 degrees for the K intermediate. In the case of BR, the stretch orientation is expected to deviate from the N-D bond orientation due to vibrational mixing in the hydrogen bonding network. In contrast, the data for the K intermediate suggest that the N-D group is not hydrogen bonded and orients along the membrane.

Graphene oxide-dependent growth and self-aggregation into a hydrogel complex of exoelectrogenic bacteria.

Abstract: Graphene oxide (GO) is reduced by certain exoelectrogenic bacteria, but its effects on bacterial growth and metabolism are a controversial issue. This study aimed to determine whether GO functions as the terminal electron acceptor to allow specific growth of and electricity production by exoelectrogenic bacteria. Cultivation of environmental samples with GO and acetate as the sole substrate could specifically enrich exoelectrogenic bacteria with Geobacter species predominating (51-68% of the total populations). Interestingly, bacteria in these cultures self-aggregated into a conductive hydrogel complex together with biologically reduced GO (rGO). A novel GO-respiring bacterium designated Geobacter sp. strain R4 was isolated from this hydrogel complex. This organism exhibited stable electricity production at >1000 μA/cm(3) (at 200 mV vs Ag/AgCl) for more than 60 d via rGO while temporary electricity production using graphite felt. The better electricity production depends upon the characteristics of rGO such as a large surface area for biofilm growth, greater capacitance, and smaller internal resistance. This is the first report to demonstrate GO-dependent growth of exoelectrogenic bacteria while forming a conductive hydrogel complex with rGO. The simple put-and-wait process leading to the formation of hydrogel complexes of rGO and exoelectrogens will enable wider applications of GO to bioelectrochemical systems.