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Biomedical subjects

E Ohtsuka

Publications and source records attributed to E Ohtsuka.

At least 271 records · Page 15Linked to original sources
PubMed1983

Raman diagnosis of nucleic acid structure: sugar-puckering and glycosidic conformation in the guanosine moiety.

Observations of Raman spectra of various nucleic acids indicate that the guanine ring breathing frequency is sensitive to the internal rotation angle around the glycosidic bond and to the conformation of the five-membered ring of the ribose residue that is directly connected with the guanine residue in question. It is found that 682 cm-1 for C2'-endo-anti, at 665 cm-1 for C3'-endo-anti, and at 625 cm-1 for C3'-endo-syn. A DNA octamer d(GpGpApApTpTpCpC) shows, in its aqueous solution, a broad Raman band at 680 cm-1 with a tail at 670 cm-1. This fact suggests that the guanosine residues in this oligomer take primarily C2'-endo-anti conformation but an appreciable amount of fluctuation of the ribose ring structure towards C3'-endo is involved.

Base Sequence↗
PubMed1983

The complete nucleotide sequence of the influenza virus neuraminidase gene of A/NJ/8/76 strain and its evolution by segmental duplication and deletion.

The neuraminidase (NA) gene from A/New Jersey (NJ)/8/76 (H1N1, formerly Hsw1 N1) strain isolated in 1976 was cloned into pBR322 and its complete nucleotide sequence was determined. The NJ8 NA gene is 1458 nucleotides long and the sequence predicted the primary structure of the NA molecule comprising of 469 amino acids with a molecular weight of 51,628. Comparison with other NA sequences of the N1 subtype strains which were isolated in 1933-1934 identified the highly variable regions at the amino-terminal stalk region and the carboxy-terminal regions. Potential glycosylation sites encoded by a 15 base-pair unit sequence are arrayed tandemly at the stalk regions. The lengths of stalk regions are highly variable because of segmental deletions in old NA genes. Possible mechanisms for such deletions are discussed.

Animals↗
PubMed1983

Behavior of the imino protons of the lambda OR3 17mer studied by high resolution NMR.

Imino proton resonances of lambda OR3 17mer were observed with time-shared Redfield pulse method by using a JEOL 500 MHz NMR instrument. They show gradual broadening and disappearance with the elevation of temperature indicating the stepwise melting of the duplex. By the selective irradiation at each peak position nuclear Overhauser effects were observed between the imino and adenine C2H protons and between imino protons themselves. Combining these data, fifteen imino proton resonances could be assigned to each base pair except two terminal AT base pairs. Based on the assignment it can be said that AT rich regions near the terminal melt first, followed by the melting of the inside GC rich core. The two AT base pairs in the middle of the GC core are resistant to heat. Spin lattice relaxation times were also observed and the results are consistent with the melting profile.

Bacteriophage lambda↗
PubMed1983

The synthesis of human growth hormone gene.

Human growth hormone gene with 584 base pairs has been synthesized by joining with DNA ligase of chemically synthesized deoxyoligonucleotides with the chain length of 15-25. The phosphotriester polymer support synthesis was employed to obtain 80 oligonucleotides.

Base Sequence↗
PubMed1982

A new condensing reagent, 1-(2,4,6-triisopropylbenzenesulfonyl)-5-(pyridin-2-yl)tetrazolide and its use in the synthesis of lambda cro binding heptadecanucleotide on a polymer support.

A new condensing reagent 1-(2,4,6,-triisopropylbenzenesulfonyl)-5-(pyridin-2-yl)tetrazolide (TPSPy) was found to give one diastereoisomer of dinucleoside monophosphate aryl esters. Several oligodeoxynucleotide blocks were prepared using this reagent. A heptadecanucleotide, dTATCCCTTGCGGTGATA, which had the same sequence as the lambda cro binding DNA sequence was synthesized by condensing mono-, tri- and dodecanucleotide blocks using this reagent on a polystyrene support.

Azoles↗
PubMed1982

E. coli initiator tRNA analogs with different nucleotides in the discriminator base position.

The effect of base changes at the fourth position from the 3'-terminus of Escherichia coli initiator tRNAMet has been studied to test the 'discriminator hypothesis' which proposed that the nucleotide in this position might have a role in the specificity of the aminoacylation reaction. E. coli initiator tRNA lacking the 3'-terminal tetranucleotide was prepared by partial digestion with S1 nuclease. To construct tRNA analogs with different bases in the fourth position this truncated tRNA was joined by RNA ligase to each of four chemically synthesized 2',3'-ethoxy-methylidene tetranucleotides pACCA(em), pCCCA(em), pGCCA(em), and pUCCA(em). In vitro aminoacylation studies showed that all four molecules accepted methionine, albeit with different Vmax values.

Base Sequence↗
PubMed1982

Studies on deoxyribonucleic acids and related compounds. V. Synthesis of pentadecanucleotide duplex containing the ideal Pribnow sequence of promoter by the phosphotriester method using a new phosphorylating reagent.

A phosphorylating reagent o-chlorophenyl phosphoro-p-anisi-dochloridate was synthesized to phosphorylate the 3'-hydroxyl group of N, 5'-protected deoxynucleosides. These nucleotides served as 3'-terminal units for the synthesis of oligonucleotide blocks. By condensation of these oligonucleotide blocks the partially complementary deoxypentadecanucleotides dAGCTTATAATGC-TCG and dAGCTCGAGCATTATA, which contained the ideal Pribnow sequence TATAATG, were synthesized.

Base Sequence↗
PubMed1982

NMR studies of base-pairing in 15N-labeled ribotetranucleotide GGCUp.

95% N-15 enriched ribotetranucleotide GGCUp was prepared. Its aqueous solution gives three imino-proton resonances at 10.6, 12.0 and 13.6 ppm. The peak at 10.6 ppm split by N-15 into a doublet with coupling constant 90 Hz. On the preirradiation at this peak, the intensity of the 12.0 ppm peak decreased and the peak at 13.6 ppm remained unchanged. Therefore the 10.6 ppm peak was unambiguously assigned to the G imino proton and the 12.0 ppm peak to the U imino proton in the G:U base pair. By raising temperature the former two peaks coalesced at around 25 degrees C, while the signal of the G imino proton in the G:C pair was observed up to 35 degrees C. The G:U base pair seems to be disrupted first, then the break of the G:C pair is followed. Temperature dependences of the CH proton, N-15 and P-31 nuclei resonances were also measured.

Kinetics↗
PubMed1981

Characterization of nascent DNA fragments produced by excision of uracil residues in DNA.

Nascent short DNA chains could result from repair of incorporated uracil residues or be intermediates in discontinuous replication. We have characterized short DNA chains having apyrimidinic/apurinic-sites at 5' ends, the expected intermediates of repair, to distinguish them from RNA-linked replication intermediates. We have synthesized model substrates for the repair products; d(pRib[32P]poly(T)) and d(Rib[32P]poly(T)). Alkaline hydrolysis of both substrates has produced [5'-32P]poly(dT). Nascent short DNA was prepared from an Escherichia coli sof (dut) mutant, in this strain fragments from excision repair of uracil residues accumulate. The products of alkaline treatment are hardly digested by spleen exonuclease which selectively degrades 5'-hydroxyl-terminated DNA. These two results show that alkaline hydrolysis of the uracil repair fragments produces 5'-phosphoryl-terminated DNA, whereas it is known that 5'-hydroxyl-terminated DNA is generated from RNA-linked DNA molecules. The two types of nascent fragments thus can be distinguished by the 5'-terminal structure produced by an alkaline hydrolysis.

Animals↗
PubMed1981

Studies on transfer ribonucleic acids and related compounds. XL. Synthesis of an eicosaribonucleotide corresponding to residues 35-54 of tRNAfMet from E. coli.

An E. coli tRNAfMet fragment [C-A-U-A-A-C-C-C-G-A-A-G-G-U-C-G-U-C-G-G (bases 35-f54)] containing the anticodon triplet has been synthesized by the phosphotriester method involving protected oligonucleotide blocks. Di- or tri-nucleotide blocks were prepared by condensation of 2'-O-(o-nitrobenzyl) nucleotide derivatives and used for the synthesis of pentanucleotide blocks. The 5'-hydroxy, heterocyclic amino and internucleotide linkage were protected with monomethoxytrityl, acyl and p-chlorophenyl groups, respectively. The 3'-phosphates of the pentanucleotides, except for the GUCGG block where 2'-O-benzoyl 3'-O-(o-nitrobenzyl) N-isobutyrylguanosine was used, were protected with p-chlorophenyl and anilido groups. The anilido groups were removed by treatment with isoamyl nitrite and the 3'-phosphodiesters of resulting pentamers were activated with mesitylenesulfonyl nitrotriazolide to give protected decanucleotides in yields of 61-89%. The two decanucleotides were condensed similarly to yield the protected eicosanucleotide in a yield of 59%. The product was deblocked and purified by ion-exchange chromatography on DEAE-Sephadex A-25 and characterized by enzymatic hydrolysis after labelling the 5'-end by phosphorylation using polynucleotide kinase and [gamma-32P]ATP.

Anticodon↗