Kazuhisa Okada

Learn More
Codon usages are known to vary among vertebrates chiefly due to variations in isochore structure. Under the assumption that marked differences exist in isochore structure between warm-blooded and cold-blooded animals, the variations among vertebrates were previously attributed to an adaptation to homeothermy. However, based on data from a turtle species and(More)
This paper describes the first synthesis of phosmidosine and phosmidosine B, i.e., nucleotide antibiotics composed of 8-oxoadenosine and L-proline which are connected via a unique N-acyl phosphoramidate linkage. Phosmidosine has a yet-undetermined chiral center at the phosphorus atom of the N-acyl phosphoramidate linkage. Phosmidosine B is a demethylated(More)
Phosmidosine and a variety of its analogs were synthesized by reaction of N-diisopropyl-N'-(N tritylaminoacyl)phosphorodiamidite derivatives with appropriately protected 8-oxoadenosine derivatives. It was found that replacement of the methyl group of the N-acylphosphoramidate linkage with longer alkyl groups resulted in significant stabilization of the(More)
To study the structure-activity relationship of phosmidosine, a variety of phosmidosine derivatives 9a-g were synthesized by condensation of N-diisopropyl N'-(N-tritylprolyl)phosphorodiamidite 6 with appropriately protected nucleoside derivatives 7a-g. As the result, replacement of the 7,8-dihydro-8-oxoadenine base by adenine and 6-N-acetyladenine did not(More)
Phosmidosine is known to have potent antitumor activity and the unique property of stopping cell growth at the G(1) phase in the cell cycle. However, this natural product having N-prolylphosphoramidate and O-methyl ester linkages on the 5'-phosphoryl residue is unstable under basic conditions and even during the chemical synthesis due to its inherent methyl(More)
This paper deals with the synthesis of a stable biotin-phosmidosine conjugate molecule 3 that is required for isolation of biomolecules that bind to phosmidosine (1). It was found that introduction of a biotin residue into the 6-N position of phosmidosine could be carried out by reaction of an N7-Boc-7,8-dihydro-8-oxoadenosine derivative 13 with phenyl(More)
  • 1