Toshimasa Ishida

Cooperative stacking and hydrogen bond pairing interactions of fragment peptide in cap binding protein with mRNA cap structure

The stacking and hydrogen bonding abilities of Trp-(Gly)n-Glu (n = 0 approximately 3) for the interaction with 7-methylguanine (m7G) base were examined by fluorescence and 1H-NMR methods, and it was shown that they correlate with the distance between the Trp and Glu residues, and become most significant when both residues are separated from each other by two Gly residues (n = 2). Based on this insight, the sequence conserved between the human and yeast cap binding proteins (CBPs) was surveyed, and the sequence of Trp-Glu-Asp-Glu (No. 102-105 in human CBP) was selected as a probable site for the binding with mRNA cap structure. Thus, the stacking and hydrogen bonding abilities of Trp-Glu-Asp-Glu with m7G cap structure were examined by comparative experiments using its analogous peptides. The results showed that the fourth Glu residue is important not only for the construction of hydrogen bond pairing with m7G base but also for strengthening the stacking interaction between the Trp indole ring and m7G base. Taking account of the recognition analysis using the mutant CBP proteins by site-directed mutagenesis (Ueda, H., Iyo, H., Doi, M., Inoue, M., Ishida, T., Morioka, H., Tanaka, T., Nishikawa, S. and Uesugi, S. (1991) FEBS Lett. 280, 207-210), this cooperative interaction could be important for the recognition of mRNA cap structure.

Combination of Trp and Glu residues for recognition of mRNA cap structure : analysis of m7G base recognition site of human cap binding protein (IF-4E) by site-directed mutagenesis

Four mutants of the human cap binding protein (hCBP), in which Trp‐102, Glu‐103, Asp‐104 or Glu‐105 was changed to the aliphatic Leu or Ala, were prepared, and their cap binding abilities were examined. Cap binding abilities of two mutants. W102L (Trp‐102→Leu) and E105A (Glu‐105→Ala), were significantly decreased in comparison with the wild‐type hCBP. This result suggest that Trp‐102 and Glu‐105 are both necessary for the cap binding, and the most probable binding mode with the m7G of cap structure is the combination of the stacking by Trp‐102 and the hydrogen‐bond pairing by Glu‐105, as was already proposed from the model studies.

Structure of ranitidine hydrochloride

N-(2-{[5-(dimethylaminomethyl)-2-furanyl» methylthio} ethyl)-N-methyl-2-nitro-1,1-ethenediamine hydrochlorure, C 13 H 23 N 4 O 3 S + • Cl − , cristallise dans P2 1 /n avec a=18,708, b=12,980, c=7,204 A, β=95,09 o , Z=4, affinement jusqua R=0,047. Latome N du groupe dimethylamine possede un proton qui donne une liaison hydrogene avec lion Cl − de groupement N-ethyl-N-methyl-2-nitro-1,1-ethenediamine prend une conformation dans laquelle les atomes NH, de lamine CH de lethene et O du nitro sont desordonnes. Lensemble de la molecule ranitidine a une conformation ouverte, dans laquelle la chaine laterale est spirale

Patellamide A, a cytotoxic cyclic peptide from the ascidian Lissoclinum patella.

The structure of crystals of patellamide A (13-methyl-9,23-bis(1-methylethyl)-2,16-bis(1-methylpropyl)-14,-28-di oxa-7,21- dithia-3,10,17,24,29,30,31,32- octaaza-pentacyclo[24.2.1.1(5,8).1(12,15).1(19,22]dotriac onta-1(29),5,- 8(30),15(31),19,22(32)-hexaene-4,11,18,25-tetraone methanol solvate monohydrate, C35H49N8O6S2.-CH4O.H2O), a cytotoxic cyclic peptide having a non-C2-symmetric methyl group, shows the C2-symmetric and saddle-shaped rectangular conformation where the methyl group is disordered into two C2-symmetric positions. The water and methanol solvents were located on the crystallographic diad axis and were held by hydrogen bonds and van der Waals contacts with the polar ring N atoms and non-polar D-Val side-chain atoms, respectively.

Structure of ascidiacyclamide as the ethanol water solvate, a cytotoxic cyclic peptide from Ascidian

The X-ray crystal structure determination of the C2H5OH.H2O solvate of ascidiacyclamide (C36H52N8O6S2), a cytotoxic cyclic peptide from marine tunicate Ascidian, revealed a C2-symmetric saddle-shaped rectangular conformation of the molecule. The water and ethanol molecules are located on the crystallographic diad axis and are held by hydrogen bonds and van der Waals contacts with the polar ring N atoms and nonpolar D-Val side-chain atoms, respectively. The molecular conformation and the interaction with solvent molecules are nearly the same as those of the compound with C2H5OH.2H2O [Ishida, In, Doi, Inoue, Hamada & Shioiri (1992). Biopolymers, 32, 131-143].

The highly solvated structure of theonellapeptolide Id, a tridecapeptide lactone from the Okinawa marine sponge Theonella swinhoei

Theonellapeptolide Id (TNLP-Id), C 70 H 125 N 13 O 16 .12H 2 O, was crystallized from an aqueous methanol solution. This crystalline cyclic tridecapeptide is solvated by 12 water molecules, which interact with the backbone. All the solvent molecules are located on one face of the hydrophobic peptide. This suggests that the molecule also has unanticipated amphipathic properties. The uniquely folded cyclic backbone is composed of short and long turn units.

Effect of the neighbouring oxygenated substituent on asymmetric reduction with Hantzsch-type 1,4-dihydropyridines having a chiral sulfinyl group

Introduction of the oxygen substitutent at C-6 of the Hantzsch-type compound having a sulfinyl group at C-5 affects the reduction of ketones with respect to both reactivity and stereoselectivity.

First stereoselective total synthesis of macrocarpal C: structure elucidation of macrocarpal G

The first stereoselective total synthesis of macrocarpal C is achieved via a coupling reaction of a silyl dienol ether with a novel hexasubstituted benzene chromium tricarbonyl complex as an optically active benzyl cation equivalent, thereby clarifying the identity of macrocarpal C and G.

Selective binding of guanine base by a tryptophan-containing dipeptide

The crystal structure of the m7GMP–Trp-Glu (1:1) complex crystal shows the tight linkage of the guanine base with the peptide backbone chain via triple hydrogen bonds and a prominent stacking formation with the indole ring of tryptophan; this suggests the importance of a combination of these means for the selective binding of the guanine base by protein.

Structure of 5-hydroxyindole-3-acetic acid

C 10 H 9 NO 3 cristallise dans P2 1 /c avec a=5,892, b=5,141, c=29,305 A, β=102,61 o , Z=4; affinement jusqua R=0,053. La molecule adopte une conformation plane dans laquelle langle diedre du cycle indole et du groupement carboxyl est de 175,5 o . Les molecules du cristal sont maintenues par des liaisons hydrogene entre les groupements carboxyl centrosymetriquement apparentes, entre les groupements hydroxyl, et entre NH (indole) et O (carboxyl)