Active site phosphoryl groups in the biphosphorylated phosphotransferase complex reveal dynamics in a millisecond time scale

AbstractThe N-terminal domain of Enzyme I (EIN) and phosphocarrier HPr can form a biphosphorylated complex when they are both phosphorylated by excess cellular phosphoenolpyruvate. Here we show that the electrostatic repulsion between the phosphoryl groups in the biphosphorylated complex results in characteristic dynamics at the active site in a millisecond time scale. The dynamics is localized to phospho-His15 and the stabilizing backbone amide groups of HPr, and does not impact on the phospho-His189 of EIN. The dynamics occurs with the kex of ∼500s−1 which compares to the phosphoryl transfer rate of ∼850s−1 between EIN and HPr. The conformational dynamics in HPr may be important for its phosphotransfer reactions with multiple partner proteins.Structured summary of protein interactionsEIN and HPr bind by nuclear magnetic resonance (View Interaction)

Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid

Wave reflection and transmission by curtainwall-pile breakwaters using circular piles

author's final versionThis paper presents a mathematical model which computes the hydrodynamic characteristics of a curtainwall-pile breakwater using circular piles, by modifying the model developed for rectangular piles by Suh et al. in 2006. To examine the validity of the model, laboratory experiments have been conducted for curtainwall-pile breakwaters with various values of draft of curtain wall, spacing between piles, and wave height and period. Comparisons between measurement and prediction show that the mathematical model adequately reproduces most of the important features of the experimental results. The mathematical model based on linear wave theory tends to over-predict the reflection coefficient as the wave height increases. As the draft of the curtain wall increases and the porosity between piles decreases, the reflection and transmission coefficient increases and decreases, respectively, as expected. As the relative water depth increases, however, the effect of porosity disappears because the wave motion is minimal in the lower part of a water column for short waves

Some statistical characteristics of large deepwater waves around the Korean Peninsula

The relationship between significant wave height and period, the variability of significant wave period, the spectral peak enhancement factor, and the directional spreading parameter of large deepwater waves around the Korean Peninsula have been investigated using various sources of wave measurement and hindcasting data. For very large waves comparable to design waves, it is recommended to use the average value of the empirical formulas proposed by Shore Protection Manual in 1977 and by Goda in 2003 for the relationship between significant wave height and period. The standard deviation of significant wave periods non-dimensionalized with respect to the mean value for a certain significant wave height varies between 0.04 and 0.21 with a typical value of 0.1 depending upon different regions and different ranges of significant wave heights. The probability density function of the peak enhancement factor is expressed as a lognormal distribution, with its mean value of 2.03, which is somewhat smaller than the value in the North Sea. For relatively large waves, the probability density function of the directional spreading parameter at peak frequency is also expressed as a lognormal distribution

Performance Comparison of Spectral Wave Models Based on Different Governing Equations Including Wave Breaking

The performance of three spectral wave models based on different types of governing equations, REF/DIF S, MIKE 21 BW module and SWAN, was compared by using four laboratory and field experimental data. The comparison was focused on accurate prediction of the measured wave height. Characteristics of the three wave models were discussed and their overall predictability of the measured data was evaluated by calculating mean absolute relative errors of wave height. All the numerical models simulated fairly well shoaling and breaking of waves propagating on a plane sloping beach, but the model accuracy was somewhat degenerated in simulating waves propagating over a barred beach. Among the three models, MIKE 21 BW was the most insensitive to the bathymetric change. Combined refraction-diffraction over a shoal without breaking was quite well simulated by the models, especially by REF/DIF S and MIKE 21 BW. When waves break over the shoal, however, all the models failed to reproduce the wave field behind the shoal. The agreement with data in simulating wave diffraction around breakwater was remarkably good for MIKE 21 BW, but very poor for other two models. Except the last simulation, the mean absolute relative errors of wave height from the three models ranged between 3 and 27%

Calculation of expected sliding distance of breakwater caisson considering variability in wave direction

In this study, the reliability design method developed by Shimosako and Takahashi in 2000 for calculation of the expected sliding distance of the caisson of a vertical breakwater is extended to take into account the variability in wave direction. The effects of directional spreading and the variation of deepwater principal wave direction about its design value were found to be minor compared with those of the obliquity of the deepwater design principal wave direction from the shore-normal direction. Reducing the significant wave height at the design site by 6% to correct the effect of wave refraction when using Godas model was found to be appropriate when the deepwater design principal wave direction was about 20 degrees. When we used the field data in a part of the east coast of Korea, taking the variability in wave direction into account reduced the expected sliding distance to about one third of that calculated without taking the variability in wave direction into account, and the required caisson width was reduced by about 10 % at the maximum.author's final versio

Experimental verification of horizontal two-dimensional modified mild-slope equation model

In order to verify modified mild-slope equation models in a horizontal two-dimensional space, a hydraulic experiment is made for surface wave propagation over a circular shoal on which water depth varies substantially. A horizontal two-dimensional numerical model is also constructed based on the hyperbolic equations that have been developed from the modified mild-slope equation to account for the substantial depth variation. Comparison between experimental measurements and numerical results shows that the modified mild-slope equation model is capable of producing accurate results for wave propagation in a region where water depth varies substantially, while the conventional mild-slope equation model gives large errors as the mild-slope assumption is violated.author's final versio

Green Tea Consumption and Stomach Cancer Risk: A Meta-Analysis

OBJECTIVES: Green tea has been suggested to have a chemopreventive effect against various cancers including stomach cancer. The aim of this study is to elucidate the relationship between green tea consumption and stomach cancer risk by meta-analysis. METHODS: Eighteen observational studies were identified using MEDLINE, THE COCHRANE LIBRARY, RISS, and a manual search. Summary relative risks/odds ratios (RR/ORs) for the highest versus non/lowest green tea consumption levels were calculated on the basis of fixed and random effect models. Subgroup analyses were used to examine heterogeneity across the studies. RESULTS: The combined results indicate a reduced risk of stomach cancer with intake of green tea (RR/OR=0.86, 95% CI=0.74-1.00). Subgroup analysis with six studies that reported differences between the highest and lowest consumption levels equal to or greater than five cups/day revealed a statistically significant protective effect (RR/OR=0.68, 95% CI=0.53-0.87). CONCLUSION: Green tea appears to play a protective role against the development of stomach cancer. The results also suggest that a higher level of green tea consumption might be needed for a clear preventive effect to appear. This conclusion, however, should be interpreted with caution because various biases can affect the results of a meta-analysis.ope