Saikusa K.,Yokohama City University |
Fuchigami S.,Yokohama City University |
Takahashi K.,Yokohama City University |
Takahashi K.,Chugai Research Institute for Medical Science Inc. |
And 8 more authors.
Analytical Chemistry | Year: 2013
The minimum structural unit of chromatin is the nucleosome core particle (NCP), consisting of 146 bp of DNA wrapped around a histone octamer, which itself contains two H2A/H2B dimers and one (H3/H4)2 tetramer. These multimers possess functionally important tail regions that are intrinsically disordered. In order to elucidate the mechanisms behind NCP assembly and disassembly processes, which are highly related to gene expression, structural characterization of the H2A/H2B dimer and (H3/H4)2 tetramer will be of importance. In the present study, human histone multimers with disordered tail regions were characterized by electrospray ionization (ESI) ion mobility-mass spectrometry (IM-MS) and molecular dynamics (MD) simulation. Experimentally obtained arrival times of these histone multimer ions showed rather wide distributions, implying that multiple conformers exist for each histone multimer in the gas phase. To examine their structures, MD simulations of the histone multimers were performed first in solution and then in vacuo at four temperatures, resulting in a variety of histone multimer structures. Theoretical collision cross-section (CCS) values calculated for the simulated structures revealed that structural models with smaller CCS values had more compact tail regions than those with larger CCS values. This implied that variation of the CCS values of the histone multimers were primarily due to the random behaviors of the tail regions in the gas phase. The combination of IM-MS and MD simulation enabled clear and comprehensive characterization of the gas-phase structures of histone multimers containing disordered tails. © 2013 American Chemical Society. Source
Saikusa K.,Yokohama City University |
Saikusa K.,Hiroshima University |
Shimoyama S.,Yokohama City University |
Shimoyama S.,Jasco International Co. |
And 7 more authors.
Protein Science | Year: 2015
It is well known that various modifications of histone tails play important roles in the regulation of transcription initiation. In this study, some lysine (Lys) and arginine (Arg) residues were acetylated and deiminated, respectively, in the histone H2A/H2B dimer, and charge-neutralization effects on the dimer structure were studied by native mass spectrometry. Given that both acetylation and deimination neutralize the positive charges of basic amino acid residues, it had been expected that these modifications would correspondingly affect the gas-phase behavior of the histone H2A/H2B dimer. Contrary to this expectation, it was found that Arg deimination led to greater difficulty of dissociation of the dimer by gas-phase collision, whereas acetylation of Lys residues did not cause such a drastic change in the dimer stability. In contrast, ion mobility-mass spectrometry (IM-MS) experiments showed that arrival times in the mobility cell both of acetylated and of deiminated dimer ions changed little from those of the unmodified dimer ions, indicating that the sizes of the dimer ions did not change by modification. Charge neutralization of Arg, basicity of which is higher than Lys, might have triggered some alteration of the dimer structure that cannot be found in IM-MS but can be detected by collision in the gas phase. © 2015 The Protein Society. Source
Kisco Company | Date: 1948-07-27
DEFLECTOR TYPE AIR CIRCULATORS EMPLOYING ELECTRICALLY DRIVEN FANS, INCLUDING FLOOR MODELS, DESK MODELS AND VERTICAL OR COLUMN TYPE CIRCULATORS, AND CEILING CIRCULATORS.
Kisco Company | Date: 1951-02-13
AIR CIRCULATING DEVICES EACH EMBODYING A FAN AND A BAFFLE ADJACENT THERETO, AND COMPRISING MODELS FOR FLOOR, TABLE OR CEILING SUPPORT.
Kisco Ltd., University of Tokyo and Daisankasei Co. | Date: 2012-06-22
Provided is: a cell culture membrane, which is free from materials derived from living organisms, can easily be industrially mass-produced, exhibits superior long-term storage properties and chemical resistance, has excellent cell adhesion properties and long-term culture properties and is capable of replicating a cell adhesion morphology that is similar to that of collagen derived from living organisms and being used for conventional cell cultivation. Also provided are a cell culture substrate, and a method for manufacturing the cell culture substrate. In the present invention, as a cell adhesion layer, a polymer membrane represented by formula (I) is formed on the base of a cell culture substrate so as to have a membrane thickness equal to or greater than 0.2 m (in the formula, R1 and R2 represent a (CH