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Biomedical subjects

Akio Kobori

Publications and source records attributed to Akio Kobori.

27 records · Page 2Linked to original sources
PubMed2004

Separation of mismatched DNA by using the affinity column immobilizing mismatch-binding ligands.

Mismatch binding ligands (MBL), ND and NA, bind to DNA containing mismatch base pairs. These MBLs were immobilized to NHS-activated affinity column via amine linker. Affinity chromatographic analyses of mismatched DNAs by using the ND-immobilized column showed clear separation of G-G and G-A from other mismatched DNAs. The results of the NA-immobilized column also showed good separation of A-A, G-A, G-G, A-C from other mismatched DNAs. The order of mobility of mismatched duplexes on MBL-immobilized column was in good agreement with that of the binding affinity in a solution phase obtained by the melting temperature measurement.

Base Pair Mismatch↗
PubMed2004

SPR fingerprinting of mismatched base pair.

Discrimination of mismatched base pairs having various flanking sequence from normal Watson-Crick base pairs were examined using SPR sensor surface where mismatch binding ligand (MBL) were immobilized. CC, CT, and TT mismatched base pair are distinguishable from wild type DNA by means of diaminonaphthyndine dimer (damND) immobilized sensor surface. By comparing the component ratio of responses obtained by MLB immobilized sensors, distinct differences could be observed between mismatched base pairs having almost the same total SPR response.

Base Pair Mismatch↗
PubMed2003

Detection of the C-C mismatched base pair by small ligands.

We synthesized 2-aminonaphthyridine derivatives that specifically bind to cytosine-cytosine (C-C) mismatch. The binding of ligands was verified by observing an increase of melting temperature for 11-mer duplexes containing a mismatch in the presence of ligands. It was found that the aminonaphthyridine dimer stabilized C-C mismatch more strongly than the monomer.

Base Pair Mismatch↗
PubMed2003

The binding of naphthyridine tetramer to guanine-rich sequences.

A dimeric form of 2-amino-1,8-naphthyridine derivative ND binds to human telomeric sequence d(TTAGGG)n by strong stabilization of G-G mismatches in the hypothetical duplex of the sequence, and inhibits the elongation of the sequence by telomerase. To gain higher affinity to the telomeric sequence, we have synthesized naphthyridine tetramer NT which contains four naphthyridine chromophores. Tm measurements of the telomeric sequence in the presence of NT and ND indicated that NT binds more strongly to the telomeric sequence than ND. Electrospray ionization mass spectorometry of the complex between NT and 15-mer telomeric sequence clearly showed that one molecule of NT bound to the 15-mer sequence. This suggested that the 15-mer forms hairpin-like structure in the complex, and the resultant of the G-G mismatches were stabilized by NT.

Base Sequence↗
PubMed2003

2,6-Diaminonaphthyridine derivatives bind to a single nucleotide bulge in DNA.

2,6-Diamino-1,8-naphthyridine derivative (daNpt), which possesses hydrogen bonding groups in an alignment of donor-acceptor-acceptor-donor binds to a single nucleotide bulge in the duplex. The melting temperatures (Tm) of all duplexes containing a bulge were increased, especially for the cytosine (C) and thymine (T) bulges, in the presence of daNpt, whereas only a small increase of Tm was observed for the fully matched duplexes. It was suggested by pH dependency of Tm and UV spectra, that a protonation of daNpt should play an important role for the recognition of C and T bulges.

Base Sequence↗
PubMed2002

A new method for the synthesis of oligodeoxyribonucleotides containing 4-N-alkoxycarbonyldeoxycytidine derivatives and their hybridization properties.

Oligodeoxyribonucleotides incorporating 4-N-alkoxycarbonyldeoxycytidine derivatives were synthesized on polystyrene-type ArgoPore resins having a new benzyloxy(diisopropyl)silyl linker, by use of ZnBr(2) as the detritylating agent. The first 3'-terminal thymidine could be attached to the resin by successive in situ reactions of 5'-O-DMTr-thymidine with diisopropylsilanediyl ditriflate and an ArgoPore resin containing hydroxyl groups. The use of this new silanediyl-type linker allowed release of the DNA chain from the resin by treatment with TBAF under neutral conditions. The T(m) experiments apparently showed that incorporation of 4-N-alkoxycarbonyldeoxycytidines into DNA strands resulted in higher hybridization affinity with the complementary DNA strands than that of 4-N-acyldeoxycytidines. In addition, comparable T(m) studies using oligodeoxyribonucleotides incorporating acyl (RC(O)-) groups and alkoxyacyl (RO(CH(2))(n)C(O)-) groups having the same chain length show that the latter tend to exhibit higher T(m) values than the former. It turned out that 4-N-alkoxycarbonyldeoxycytidines can form base pairs not only with deoxyguanosine but also with deoxyadenosine. Based on the ab initio calculations of the hydrogen bond energies of the possible base pairs formed between 4-N-methoxycarbonyl-1-methylcytosine and 9-methyladenine and the NMR analysis of the base-pairs of (15)N-labeled 4-N-alkoxycarbonyldeoxycytidines with deoxyadenosine derivatives, we conclude that the base pair involves two unique hydrogen bonds between the cytosyl 4-NH group and the adenyl N(1) atom and between the O atom of the ester group and the adenyl 6-NH group.

Adenosine↗
PubMed2002

Hybridization ability and base pair geometry of modified deoxycytidine derivatives having a 4-N-carbamoyl group.

Modified oligodeoxyribonucleotides incorporating 4-N-carbamoyldeoxycytidine derivatives were synthesized. The 1H-NMR of 4-N-carbamoyldeoxycytidine suggests that the carbamoyl group forms an intramolecular hydrogen bond with the cytosine ring nitrogen atom and this geometry would inhibit formation of the Watson-Crick base pair with a guanine base. However, the Tm analysis of the modified oligodeoxynucleotides revealed that, in the process of their hybridization with the complementary oligodeoxynucleotides, the orientation of the carbamoyl group changed in a manner where the stable Watson-Crick base pair can be formed with the guanine base.

Base Pairing↗
PubMed2002

Binding analysis between naphthyridine dimers and GG mismatch DNA.

Kinetics and thermodynamics studies of the binding between naphthyridine dimer and DNA duplexes having a G-G mismatch sequence were performed by using Surface Plasmon Resonance (SPR) assay. Naphthyridine dimers possessing a different length of PEG linker were synthesized and immobilized to the dextran surface of the sensor chip to obtain an improved sensitivity of the SPR sensor toward a G-G mismatch. The effect of the directly neighboring base pair to the G-G mismatch was estimated from the thermodynamic parameters of the complex. These results indicate that stacking with adjacent base pair and naphthyridine dimer is the key roll for the formation of the complex between mismatched base pair and naphthyridine dimer.

Base Pair Mismatch↗