Hibiki Tomita

Learn More
Chitinases A1 and D were purified from the periplasmic proteins produced by Escherichia coli HB101 harbouring recombinant plasmids carrying respectively the chiA and chiD genes of Bacillus circulans WL-12. HPLC analysis indicated that during the hydrolysis of chitotriose, both chitinases initially produce N-acetylglucosamine and only one anomer of(More)
A new theoretical model for estimating yield of initial DNA strand break induced by several monoenergetic electrons is presented. It is based on the Monte Carlo track structure simulation and on new DNA structure models (one turn of double-strand DNA, nucleosome, solenoid), and links physical and chemical stages of radiation action. Direct and indirect(More)
We present a new Monte Carlo simulation code system (DBREAK) of the detailed events that occur when ionizing radiation interacts with water and DNA molecules. The model treats the initial energy deposition by radiation, the formation of chemically active species, subsequent diffusion-controlled chemical reactions, and induction of DNA strand breaks. DBREAK(More)
Both chitinase A1 and D from Bacillus circulans WL-12 specifically hydrolyzed the N-acetyl-beta-D-glucosaminidic bonds in 50% N-acetylated chitosan molecules to produce hetero-oligosaccharides with GlcNAc at the reducing end residues, together with GlcNAc and (GlcNAc)2. GlcN-GlcNAc and GlcN-GlcNAc-GlcNAc were produced as major hydrolysis products with(More)
The paper describes developments of the physicochemical part of a computer code system that estimates DNA strand break induction on plasmid pBR322 DNA. In order to test the reliability of the model, we evaluated the dielectric function and the time-dependent yield of chemical species in the presence of OH radical scavenger or dissolved oxygen. Results agree(More)
Plasmid pBR322 DNA (4363 base pairs) in aerobic aqueous solution was irradiated with 60Co gamma-radiation. The change of diffusion coefficients (D) of chemical species, rate constants (k) of radical-DNA interaction and solubilities of O2 in water cannot be ignored when a temperature varies more than a few tens of centigrade. It is important to examine the(More)
Biomembranes play an important role in cellular response to heat stress. In this study, we focus on the interaction between liposomes and tRNA. Upon heat treatment we determined circular dichroism spectra of tRNA in presence of liposomes prepared from POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and cholesterol (Ch). To compare thermal stability,(More)
The interaction between single-stranded RNAs and liposomes was studied using UV, Fourier Transform Infrared spectroscopy (FTIR) and Circular Dichroism spectroscopy (CD). The effect of the surface characteristics of liposomes, which were composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and modified with cholesterol (Ch) or(More)
We introduced chromosome-mediated genes into mouse thymidine kinase-deficient FM3A (FM3Atk-) cells, by electroporation. The effects of some parameters on the electric shock-mediated transfection of FM3Atk- cells were investigated. Gene transfer of mouse L929 metaphase chromosome DNA into FM3Atk- resulted in a maximum frequency of (3.0 +/- 0.3) x 10(-5) at a(More)
An electrostatic discharge is known to be a noise source and causes the malfunction of electronic circuits. As a result, most of the studies to date have been made on electromagnetic noise radiated by electrostatic discharges. Here, the authors focus on the effect of an electrostatic field on electronic circuits. The electrostatic field strength of(More)