Search PubMed⌕ Search

Biomedical subjects

T Shimidzu

Publications and source records attributed to T Shimidzu.

29 records · Page 2Linked to original sources
PubMed1986

An approach to DNA fragment synthesis from unprotected nucleoside.

Oligodeoxynucleotides have been synthesized from unprotected nucleoside by use of morpholinophosphordichloridite as a phosphorylating reagent. This procedure consists of three (in situ) steps; the reaction of 5'-O-protected deoxynucleotide with morpholinophosphordichloridite, the reaction of the resulting on active mononucleotide derivative with the second nucleoside, non-aqueous oxidation, and then removal of amino moiety at phosphate diester linkage.

Base Sequence↗
PubMed1985

A rapid synthesis of a DNA fragment using an unprotected nucleoside and a phosphine derivative.

A rapid synthesis of DNA fragment from unprotected nucleoside and phosphine derivative, morpholinophosphordichloridite, has been studied, demonstrating a d(T-T) and its amino-phosphonate derivative syntheses. A high selectivity of this reagent eliminates the protection of nucleoside hydroxyl groups. The P-N bond in the resulting dinucleoside phosphite can readily be converted to a phosphite triester with alcohol and to the corresponding aminophosphonate by a non-aqueous oxidation with m-chlorobenzoic acid. The P-N bond in the phosphate link is very stable and so provides a protection for the phosphoryl group which has many potential uses. Deprotection can be achieved by a simple treatment with NH2OH.

DNA↗
PubMed1984

A simple and convenient synthesis of 3'-5'- or 2'-5'-linked oligoribonucleotide by polymerization of unprotected ribonucleoside using phosphorus tris-azole.

Oligoribonucleotides have been synthesized directly from unprotected ribonucleosides by a chemical polymerization approach using phosphorus tris-azoles. The procedure involves two steps: (i) the reaction of unprotected ribonucleoside with phosphorus tris-azole and (ii) the in situ oxidation of the resulting phosphite with iodine and water. Several phosphorus tris-azoles were investigated for generating oligoribonucleotide chains. Phosphorus tris-azoles of which azoles are imidazole, 2-methylimidazole, and 2-ethyl-4-methylimidazole were found to be most effective. Uridine, adenosine, and cytidine oligonucleotides were obtained rapidly in high yields without any protection. The inter-ribonucleotidic linkage of the oligomers consists of 3'-5'- and 2'-5'-linkages. The linkage isomers were easily separated by a reverse phase column chromatography. The present approach provides a convenient and potentially useful method for preparing 3'-5'- or 2'-5'-linked oligoribonucleotides.

Animals↗
PubMed1982

Radiation-induced reactions of thymine, thymidine and thymidine-5'-monophosphate in aqueous solutions.

Radiochemical reactivities of thymine (T), thymidine (Td), thymidine-3' and 5'-monophosphates (3'-, 5'-TMP) and thymidylyl (3' leads to 5') thymidine (TpT) varied in the following order: [A] T (G-value for decomposition, 1.81) less than Td (2.14) less than 3'-TMP = TpT (2.51) less than 5'-TMP (2.76) in deaerated aqueous solution; [B] TpT (2.82) less than T (3.17) congruent to Td (3.18) less than 3'-TMP (3.49) less than 5'-TMP (3.65) in N2O-saturated aqueous solution; [C] T (2.70) congruent to TpT (2.73) less than Td (2.81) less than 3'-TMP = 5'-TMP (3.47) in deaerated aqueous solution containing sodium formate.

Aerobiosis↗
PubMed1979

Synthesis of cationic cyclo-oligo(ethyleneadenine).

A novel cationic and cyclic oligo (ethyleneadenine) whose main chain has adenine ring was synthesized by the thermal polymerization of 9-(2-bromoethyl) adenine, in the solid phase. The chain extends through N-9 - N-1 and N-9 - N-7 of the adenine rings. Its molecular weight was determined to be 3960 by the sedimentation method. The micro-structure was confirmed mainly with NMR measurements. The cationic and cyclic oligo(ethyleneadenine) interacts with nucleotides and polynucleotides in neutral aqueous solution.

Adenine↗
PubMedDate not supplied

Synthesis and interactive properties of an oligonucleotide with anthraquinone at the sugar fragment.

The synthesis of a self-complementary oligonucleotide possessing an anthraquinonylmethyl substituent at the designated sugar fragment, 5'-CCU(2'AQ)AGCTAGG (1), is described. The anthraquinonylmethyl group was introduced to 2'-hydroxyl moiety of uridine, which was then converted to the protected phosphorobisdiethylamidite derivative. This reagent was used for the solid-phase synthesis of the modified oligonucleotide 1. The UV and CD melting behaviors indicate that the modified oligonucleotide 1 can form a duplex in aqueous buffer solution similar to the unmodified strand 5'-CCTAGCTAGG (7). The observed melting temperatures for the duplexes 1 and 7 were 57.4 and 40.0 degrees C, respectively. The temperature-dependent change in the intensity of the induced CD at around 335 nm reflected directly to the melting behaviors of duplex 1, indicating that the anthraquinone groups intercalate into the base pairs in the duplex. The intercalation-induced stability of the duplex translates into a free energy cost of 5.2 kcal/mol. The present work provides a novel method for enhancing the affinity of oligonucleotides for their complementary sequences.

Anthraquinones↗
PubMedDate not supplied

Synthesis and properties of an oligonucleotide modified with an acridine derivative at the artificial abasic site.

The synthesis of an oligodeoxynucleotide (ODN) modified with 2-methoxy-6-chloro-9-aminoacridine (Acr) at an abasic site is described. A stereochemically defined aminodiol, L-threoninol, was used to serve as artificial abasic nucleoside. The molecule was modified so as to be suitable for the standard phosphoramidite method and was incorporated into the interior of an ODN. In addition, N-hydroxysuccinimidyl N-[9-(6-chloro-2-methoxy)acridinyl]-6-aminocaproate has been synthesized for postsynthetic modification of the amino substrate of the L-threoninol moiety in the ODN. By using absorption spectroscopy, it is shown that oligo(dA) conjugated with acridine binds with complementary strand in a 1:1 ratio. The melting temperature showed that the nonmodified (abasic) duplex is destabilized as a result of lacking in base at the abasic site, but the covalently linked acridine ring compensates for the destabilization effect. The fluorescence quantum yield of the acridine ring was enhanced by connection to oligo(dA) and, further, by formation of a double-strand with the complementary ODN. The quantum yield is larger than that of intermolecular intercalation. The excitation spectra of Acr-ODN in the duplex is quite similar to the absorption spectra. The results indicate that the covalently linked acridine ring is selectively intercalated into the adjacent abasic site.

Acridines↗