Ryo Katahira

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We developed a microbial prescreen using Bacillus stearothermophilus NUB3620 and bacteriophage TP-68 to detect potential antitumor compounds acting on DNA or topoisomerases. During the course of screening microbial cultures for their antibacteriophage activities, we found that Streptomyces sp. isolated from a soil sample collected in Iwakuni city, Yamaguchi(More)
The three-dimensional structure of the endothelin B receptor (ETB) selective antagonist RES-701-1 has been determined by 1H NMR in deuterated dimethyl sulphoxide. RES-701-1 consists of 16 amino acid residues with a novel internal linkage between the beta-carboxyl group of Asp9 and the alpha-amino group of Gly1. The structural calculations were carried out(More)
Aureolic acid group compounds, such as chromomycin A3(CHM) and mithramycin (MIT), are known as antitumor drugs. Recently we isolated a novel aureolic acid group antitumor drug, UCH9, from Streptomyces sp. The chemical structure of UCH9 is unique in that mono- (A ring) and tetrasaccharide (B-E rings) segments and a longer hydrophobic sidechain are attached(More)
MS-271 is a potent inhibitor of smooth muscle myosin light chain kinase (MLCK), obtained from Streptomyces sp. In the previous paper, we reported on the isolation, structural determination and biological properties of MS-271.(1) In this paper, we report on the three-dimensional structure of MS-271 determined by 1H NMR in deuterated dimethyl sulphoxide.(More)
An increase in the rate of protein synthesis is found to be accompanied by phosphorylation of the 40S ribosomal protein S6. Treatment of S6 by cyanogen bromide produced three fragments, and one of the fragments of S6, which is a C-terminal portion of S6 (M(r) approximately 4,000), contains all phosphorylation sites of S6. The C-terminal fragment of S6(More)
Three-dimensional structure of a human calcitonin analog (abbreviated as hCTa) in which the amino acids of the wild type are replaced at position 12, 16 and 19 by leucine residues and further at position 22 by a tyrosine residue was studied in TFE solution by 1H-NMR and distance geometry calculations. This analog has a 15-20 times activity as compared with(More)
The structure of UCH9, which is a novel antitumor agent, was determined by spectroscopic methods. UCH9 consists of an aglycone and five 2,6-dideoxy sugars (three D-olivoses, one 4-O-methyl-D-olivose and one D-oliose). Four of the five sugars are sequentially connected through a beta 1-->3 linkage (olivose-1-->3-4-O-methyl-olivose-1-->3-oliose-1-->3-+(More)
IRL 1620 ¿suc-[Glu9,Ala11,15]ET-1(8-21)¿ is a potent and specific agonist for the ET(B) receptor. Five analogs of IRL 1620 were synthesized in this study. These were all C-terminal linear peptides of endothelin 1 (ET-1) comprising 14 amino acid residues and exhibiting highly potent ET(B) receptor binding affinities. The peptides consisted of three pairs and(More)
In the eastern Seto Inland Sea, Japan, phytoplankton abundance in the surface water has gradually declined, whereas Secchi depth has risen in recent years, particularly in offshore areas. Therefore, it may be hypothesized that phytoplankton dominate light attenuation in the offshore area, and that other constituents are less important. To test this(More)
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