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201 results on '"Hifumi, Emi"'

15. Modulation of Double Zwitterionic Block Copolymer Aggregates by Zwitterion-Specific Interactions

Author

Shimizu, Akane, Hifumi, Emi, Kojio, Ken, Takahara, Atsushi, Higaki, Yuji, Shimizu, Akane, Hifumi, Emi, Kojio, Ken, Takahara, Atsushi, and Higaki, Yuji

Abstract

Transformable double hydrophilic block copolymer assemblies are valid as a biocompatible smart macromolecular system. The molecular mechanisms in the spontaneous assembly of double zwitterionic diblock copolymers composed of a poly- (carboxybetaine methacrylate) (PCB2) and a poly(sulfobetaine methacrylate) (PSB4) chains (PCB2-b-PSB4) were investigated by the modulation of the aggregates in response to nondetergent zwitterions. The PCB2-b-PSB4 diblock copolymers with a high degree of polymerization PSB4 block produced aggregates in saltfree water through “zwitterion-specific" interactions. The PCB2-bPSB4 aggregates were dissociated by the addition of nondetergent sulfobetaine (SB4) and carboxybetaine (CB2) molecules, while the aggregates showed different aggregation modulation processes for SB4 and CB2. Zwitterions with different charged groups from SB4 and CB2, glycine and taurine, hardly disrupted the PCB2-b-PSB4 aggregates. The PCB2-b-PSB4 aggregate modulation efficiency of SBs associated with the intercharge hydrocarbon spacer length (CSL) rather than the symmetry with the SB in the PSB chain. These zwitterion-specific modulation behaviors were rationalized based on the nature of zwitterions including partial charge density, dipole moment, and hydrophobic interactions depending on the charged groups and CSL.

Published
2022

17. Attomole detection of hemagglutinin molecule of influenza virus by combining an electrochemiluminescence sensor with an immunoliposome that encapsulates a Ru complex

Author

Egashira, Naoyoshi, Morita, Shin-ichi, Hifumi, Emi, Mitoma, Yoshiharu, and Uda, Taizo

Subjects
Influenza -- Diagnosis, Influenza viruses -- Physiological aspects, Influenza viruses -- Properties, Ruthenium -- Chemical properties, Ruthenium -- Optical properties, Ruthenium -- Electric properties, Biosensors -- Research, Electrochemical analysis -- Methods, Chemiluminescence -- Methods, Liposomes -- Composition, Liposomes -- Properties, Chemistry
Abstract

An immunoliposome (80 nm in diameter) encapsulating a Ru complex with two aminobutyl moieties was prepared to detect the presence of hemagglutinin molecules, which play an important role in influenza virus infection. The highly sensitive detection was accomplished by electrochemiluminescence (ECL) from the Ru complex adsorbed onto Au electrodes after competitive immunoreactions. This method clarified that the adsorption of the Ru complex onto the electrode was an important factor in obtaining high sensitivity. Optimization of the analytical conditions enabled determination of the hemagglutinin molecules of the influenza virus in the concentration range of 3 x [10.sup.-14] (6 x [10.sup.-19] mol/50 [micro]L sample) to 2 x [10.sup.-12] g/mL. The sensitivity was far superior to that obtained by conventional ELISA as well as to that obtained by biosensors and reported thus far.

Published
2008

29. Structural Diversity Problems and the Solving Method for Antibody Light Chains

Author

Hifumi, Emi

Subjects
Medical / Genetics
Abstract

The structural diversity (heterogeneity) problem of antibodies has become a big subject along with the development of antibody drugs and catalytic antibodies. The detailed studies on the subject have not been conducted because many difficult and complex problems are existed in the phenomena. The heterogeneity problem is observed in a whole antibody as well as a catalytic antibody. The difficulty and complexity of the heterogeneity are in the generation of many isoforms caused by different charges, different molecular sizes, and/or modifications of amino acid residues. We found that the constant region domain of the antibody light chain also plays an important role in the heterogeneity. It is desirable that the antibody and/or the subunits must have a defined structure for practical use. We found interesting phenomena that copper ion can convert the multi-molecular forms of antibodies to mono-molecular forms. The ion contributed greatly to the enrichment of the dimer-form and the homogenation of the differently charged full-length and constant region domain of the light chain. The role of copper ion must be significant for preparing a single, defined, not multiple, isoform structure. Note that the big problem could be solved by using copper ion during the purification process.

Published
2018

38. Biochemical Features of a Catalytic Antibody Light Chain, 22F6, Prepared from Human Lymphocytes

Author

Hifumi, Emi, Fujimoto, Naoko, Arakawa, Mitsue, Saito, Eri, Matsumoto, Shingo, Kobayashi, Nobuyuki, Uda, Taizo, Hifumi, Emi, Fujimoto, Naoko, Arakawa, Mitsue, Saito, Eri, Matsumoto, Shingo, Kobayashi, Nobuyuki, and Uda, Taizo

Abstract

Human antibody light chains belonging to subgroup II of germ line genes were amplified by a seminested PCR technique using B-lymphocytes taken from a human adult infected with influenza virus. Each gene of the human light chains was transferred into the Escherichia coli system. The recovered light chain was highly purified using a two-step purification system. Light chain 22F6 showed interesting catalytic features. The light chain cleaved a peptide bond of synthetic peptidyl-4-methylcoumaryl- 7-amide (MCA) substrates, such as QAR-MCA and EAR-MCA, indicating amidase activity. It also hydrolyzed a phosphodiester bond of both DNA and RNA. From the analysis of amino acid sequences and molecular modeling, the 22F6 light chain possesses two kinds of active sites as amidase and nuclease in close distances. The 22F6 catalytic light chain could suppress the infection of influenza virus type A (H1N1) of Madin-Darby canine kidney cells in an in vitro assay. In addition, the catalytic light chain clearly inhibited the infection of the influenza virus of BALB/c mice via nasal administration in an in vivo assay. In the experiment, the titer in the serum of the mice coinfected with the 22F6 light chain and H1N1 virus became considerably lowered compared with that of 22F6-non-coinfected mice. Note that the catalytic light chain was prepared from human peripheral lymphocyte and plays an important role in preventing infection by influenza virus. Considering the fact that the human light chain did not show any acute toxicity for mice, our procedure developed in this study must be unique and noteworthy for developing new drugs., Journal of Biological Chemistry, 288(27), pp.19558-19568; 2013

Published
2013

40. A novel method of preparing the monoform structure of catalytic antibody light chain.

Author

Hifumi, Emi, Matsumoto, Shingo, Nakashima, Hiroki, Itonaga, Shogo, Arakawa, Mitsue, Katayama, Yoshiki, Kato, Ryuichi, and Uda, Taizo

Abstract

Along with the development of antibody drugs and catalytic antibodies, the structural diversity (heterogeneity) of antibodies has been given attention. For >20 yr, detailed studies on the subject have not been conducted, because the phenomenon presents many difficult and complex problems. Structural diversity provides some (or many) isoforms of an antibody distinguished by different charges, different molecular sizes, and modifications of amino acid residues. For practical use, the antibody and the subunits must have a defined structure. In recent work, we have found that the copper (Cu) ion plays a substantial role in solving the diversity problem. In the current study, we used several catalytic antibody light chains to examine the effect of the Cu ion. In all cases, the different electrical charges of the molecule converged to a single charge, giving 1 peak in cation‐exchange chromatography, as well as a single spot in 2‐dimensional gel electrophoresis. The Cu‐binding site was investigated by using mutagenesis, ultraviolet‐visible spectroscopy, atomic force microscope analysis, and molecular modeling, which suggested that histidine and cysteine residues close to the C‐terminus are involved with the binding site. The constant region domain of the antibody light chain played an important role in the heterogeneity of the light chain. Our findings may be a significant tool for preparing a single defined, not multiple, isoform structure.—Hifumi, E., Matsumoto, S., Nakashima, H., Itonaga, S., Arakawa, M., Katayama, Y., Kato, R., Uda T. A novel method of preparing the monoform structure of catalytic antibody light chain. FASEB J. 30, 895–908 (2016). www.fasebj.org [ABSTRACT FROM AUTHOR]

Published
2016
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