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Biophysics and Physicobiology

Yoshihiko Furuike, Jun Abe, Atsushi Mukaiyama, Shuji Akiyama
KaiC, a core protein of the cyanobacterial circadian clock, is rhythmically autophosphorylated and autodephosphorylated with a period of approximately 24 h in the presence of two other Kai proteins, KaiA and KaiB. In vitro experiments to investigate the KaiC phosphorylation cycle consume considerable time and effort. To automate the fractionation, quantification, and evaluation steps, we developed a suite consisting of an automated sampling device equipped with an 8-channel temperature controller and accompanying analysis software...
2016: Biophysics and Physicobiology
Yasuhiro Onoue, Rei Abe-Yoshizumi, Mizuki Gohara, Yuuki Nishino, Shiori Kobayashi, Yasuo Asami, Michio Homma
Many bacteria move using their flagellar motor, which generates torque through the interaction between the stator and rotor. The most important component of the rotor for torque generation is FliG. FliG consists of three domains: FliGN, FliGM, and FliGC. FliGC contains a site(s) that interacts with the stator. In this study, we examined the physical properties of three FliG constructs, FliGFull, FliGMC, and FliGC, derived from sodium-driven polar flagella of marine Vibrio. Size exclusion chromatography revealed that FliG changes conformational states under two different pH conditions...
2016: Biophysics and Physicobiology
Koutaro Nakagome, Katsuhiko Sato, Seine A Shintani, Shin'ichi Ishiwata
SPOC (spontaneous oscillatory contraction) is a phenomenon observed in striated muscle under intermediate activation conditions. Recently, we constructed a theoretical model of SPOC for a sarcomere, a unit sarcomere model, which explains the behavior of SPOC at each sarcomere level. We also constructed a single myofibril model, which visco-elastically connects the unit model in series, and explains the behaviors of SPOC at the myofibril level. In the present study, to understand the SPOC properties in a bundle of myofibrils, we extended the single myofibril model to a two-dimensional (2D) model and a three-dimensional (3D) model, in which myofibrils were elastically connected side-by-side through cross-linkers between the Z-lines and M-lines...
2016: Biophysics and Physicobiology
Kota Kasahara, Benson Ma, Kota Goto, Bhaskar Dasgupta, Junichi Higo, Ikuo Fukuda, Tadaaki Mashimo, Yutaka Akiyama, Haruki Nakamura
Molecular dynamics (MD) is a promising computational approach to investigate dynamical behavior of molecular systems at the atomic level. Here, we present a new MD simulation engine named "myPresto/omegagene" that is tailored for enhanced conformational sampling methods with a non-Ewald electrostatic potential scheme. Our enhanced conformational sampling methods, e.g., the virtual-system-coupled multi-canonical MD (V-McMD) method, replace a multi-process parallelized run with multiple independent runs to avoid inter-node communication overhead...
2016: Biophysics and Physicobiology
(no author information available yet)
[This corrects the article on p. 173 in vol. 13.].
2016: Biophysics and Physicobiology
Masaaki Kotera, Susumu Goto
Metabolic pathway reconstruction presents a challenge for understanding metabolic pathways in organisms of interest. Different strategies, i.e., reference-based vs. de novo, must be used for pathway reconstruction depending on the availability of well-characterized enzymatic reactions. If at least one enzyme is already known to catalyze a reaction, its amino acid sequence can be used as a reference for identifying homologous enzymes in the genome of an organism of interest. Where there is no known enzyme able to catalyze a corresponding reaction, however, the reaction and the corresponding enzyme must be predicted de novo from chemical transformations of the putative substrate-product pair...
2016: Biophysics and Physicobiology
Takako Sakano, Md Iqbal Mahamood, Takefumi Yamashita, Hideaki Fujitani
The accurate prediction of a ligand-protein complex structure is important for computer-assisted drug development. Although many docking methods have been developed over the last three decades, the success of binding structure prediction remains greatly limited. The purpose of this study was to demonstrate the usefulness of molecular dynamics (MD) simulation in assessing a docking pose predicted using a docking program. If the predicted pose is not unstable in an aqueous environment, MD simulation equilibrates the system and removes the ligand from the predicted position...
2016: Biophysics and Physicobiology
Oanh T P Kim, Manh D Le, Hoang X Trinh, Hai V Nong
Tumor necrosis factor-alpha (TNF-α) is a cytokine that plays an important role in inflammatory process and tumor development. Recent studies demonstrate that triterpene saponins from Vietnamese ginseng are efficient inhibitors of TNF-α. But the interactions between TNF-α and the saponins are still unclear. In this study, molecular docking and molecular dynamics simulations of TNF-α with three different triterpene saponins (majonoside R2, vina-ginsenoside R1 and vina-ginsenoside R2) were performed to evaluate their binding ability...
2016: Biophysics and Physicobiology
Hiroo Imai, Nami Suzuki-Hashido, Yoshiro Ishimaru, Takanobu Sakurai, Lijie Yin, Wenshi Pan, Masaji Ishiguro, Katsuyoshi Masuda, Keiko Abe, Takumi Misaka, Hirohisa Hirai
In mammals, bitter taste is mediated by TAS2Rs, which belong to the family of seven transmembrane G protein-coupled receptors. Since TAS2Rs are directly involved in the interaction between mammals and their dietary sources, it is likely that these genes evolved to reflect species-specific diets during mammalian evolution. Here, we analyzed the amino acids responsible for the difference in sensitivities of TAS2R16s of various primates using a cultured cell expression system. We found that the sensitivity of TAS2R16 varied due to several amino acid residues...
2016: Biophysics and Physicobiology
Kazunori D Yamada, Hafumi Nishi, Junichi Nakata, Kengo Kinoshita
Functional sites on proteins play an important role in various molecular interactions and reactions between proteins and other molecules. Thus, mutations in functional sites can severely affect the overall phenotype. Progress of genome sequencing projects has yielded a wealth of information on single nucleotide variants (SNVs), especially those with less than 1% minor allele frequency (rare variants). To understand the functional influence of genetic variants at a protein level, we investigated the relationship between SNVs and protein functional sites in terms of minor allele frequency and the structural position of variants...
2016: Biophysics and Physicobiology
Tatsuya Okuno, Koya Kato, Shintaro Minami, Tomoki P Terada, Masaki Sasai, George Chikenji
We discuss methods and ideas of virtual screening (VS) for drug discovery by examining the performance of VS-APPLE, a recently developed VS method, which extensively utilizes the tendency of single binding pockets to bind diversely different ligands, i.e. promiscuity of binding pockets. In VS-APPLE, multiple ligands bound to a pocket are spatially arranged by maximizing structural overlap of the protein while keeping their relative position and orientation with respect to the pocket surface, which are then combined into a multiple-ligand template for screening test compounds...
2016: Biophysics and Physicobiology
Tsukasa Nakamura, Kentaro Tomii
Comprehensive analysis and comparison of protein ligand-binding pockets are important to predict the ligands which bind to parts of putative ligand binding pockets. Because of the recent increase of protein structure information, such analysis demands a fast and efficient method for comparing ligand binding pockets. Previously we proposed a fast alignment-free method based on a simple representation of a ligand binding pocket with one 11-dimensional vector, which is suitable for such analysis. Based on that method, we conducted this study to expand and revise similarity measures of binding pockets and to investigate the effects of those modifications with two datasets for improving the ability to detect similar binding pockets...
2016: Biophysics and Physicobiology
Masayuki Oda, Takeshi Tsumuraya, Ikuo Fujii
We analyzed the correlation between the conformational strain and the binding kinetics in antigen-antibody interactions. The catalytic antibodies 6D9, 9C10, and 7C8 catalyze the hydrolysis of a nonbioactive chloramphenicol monoester derivative to generate a bioactive chloramphenicol. The crystal structure of 6D9 complexed with a transition-state analog (TSA) suggests that 6D9 binds the substrate to change the conformation of the ester moiety to a thermodynamically unstable twisted conformation, enabling the substrate to reach the transition state during catalysis...
2016: Biophysics and Physicobiology
Yuka Suzuki, Kei Yura
We investigated the effect of ATP binding to GroEL and elucidated a role of ATP in the conformational change of GroEL. GroEL is a tetradecamer chaperonin that helps protein folding by undergoing a conformational change from a closed state to an open state. This conformational change requires ATP, but does not require the hydrolysis of the ATP. The following three types of conformations are crystalized and the atomic coordinates are available; closed state without ATP, closed state with ATP and open state with ADP...
2016: Biophysics and Physicobiology
Junko Taguchi, Akio Kitao
We examine the dynamic features of non-trivial allosteric binding sites to elucidate potential drug binding sites. These allosteric sites were previously found to be allosteric after determination of the protein-drug co-crystal structure. After comprehensive search in the Protein Data Bank, we identify 10 complex structures with allosteric ligands whose structures are very similar to their functional forms. Then, possible pockets on the protein surface are searched as potential ligand binding sites. To mimic ligand binding to the pocket, complex models are generated to fill out each pocket with pseudo ligand blocks consisting of spheres...
2016: Biophysics and Physicobiology
Nobuyuki Uchikoga, Yuri Matsuzaki, Masahito Ohue, Yutaka Akiyama
Analysis of protein-protein interaction networks has revealed the presence of proteins with multiple interaction ligand proteins, such as hub proteins. For such proteins, multiple ligands would be predicted as interacting partners when predicting all-to-all protein-protein interactions (PPIs). In this work, to obtain a better understanding of PPI mechanisms, we focused on protein interaction surfaces, which differ between protein pairs. We then performed rigid-body docking to obtain information of interfaces of a set of decoy structures, which include many possible interaction surfaces between a certain protein pair...
2016: Biophysics and Physicobiology
Georgios Iakovou, Stephen Laycock, Steven Hayward
Interactive haptics-assisted docking provides a virtual environment for the study of molecular complex formation. It enables the user to interact with the virtual molecules, experience the interaction forces via their sense of touch, and gain insights about the docking process itself. Here we use a recently developed haptics software tool, Haptimol_RD, for the rigid docking of protein subunits to form complexes. Dimers, both homo and hetero, are loaded into the software with their subunits separated in space for the purpose of assessing whether they can be brought back into the correct docking pose via rigid-body movements...
2016: Biophysics and Physicobiology
Kentaro Ishii, Masanori Noda, Susumu Uchiyama
The interactions of small molecules with proteins (protein-ligand interactions) mediate various biological phenomena including signal transduction and protein transcription and translation. Synthetic compounds such as drugs can also bind to target proteins, leading to the inhibition of protein-ligand interactions. These interactions typically accompany association-dissociation equilibrium according to the free energy difference between free and bound states; therefore, the quantitative biophysical analysis of the interactions, which uncovers the stoichiometry and dissociation constant, is important for understanding biological reactions as well as for rational drug development...
2016: Biophysics and Physicobiology
Kei Yura
No abstract text is available yet for this article.
2016: Biophysics and Physicobiology
Wataru Tanaka, Mitsuo Shoji, Fumiaki Tomoike, Yuzuru Ujiie, Kyohei Hanaoka, Ryuhei Harada, Megumi Kayanuma, Katsumasa Kamiya, Toyokazu Ishida, Ryoji Masui, Seiki Kuramitsu, Yasuteru Shigeta
A uridine-cytidine kinase (UCK) catalyzes the phosphorylation of uridine (Urd) and cytidine (Cyd) and plays a significant role in the pyrimidine-nucleotide salvage pathway. Unlike ordinary ones, UCK from Thermus thermophilus HB8 (ttCK) loses catalytic activity on Urd due to lack of a substrate binding ability and possesses an unusual amino acid, i.e. tyrosine 93 (Tyr93) at the binding site, whereas histidine (His) is located in the other UCKs. Mutagenesis experiments revealed that a replacement of Tyr93 by His or glutamine (Gln) recovered catalytic activity on Urd...
2016: Biophysics and Physicobiology
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