Kazuo Yamasaki

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The structural natures of stable analogues for the ADP-insensitive phosphoenzyme (E2P) of Ca -ATPase formed in sarcoplasmic reticulum vesicles, i.e. the enzymes with bound beryllium fluoride (BeF E2), bound aluminum fluoride (AlF E2), and bound magnesium fluoride (MgF E2), were explored and compared with those of actual E2P formed from Pi without Ca 2 .(More)
Glucose transport enhancers were searched for in Lagerstroemia speciosa, a Philippine local herbal medicine used for diabetes mellitus. Bioassay-guided fractionation of the aqueous acetone extract of the leaves afforded three active ellagitannins, lagerstroemin, flosin B and reginin A, identified by NMR and optical rotation. These compounds increased(More)
Six new ent-kaurane diterpenoid glycosides, cussoracosides A (3), B (4), C (5), D (6), E (7), and F (8) were isolated from the dried leaves of Cussonia racemosa, along with two known compounds identified as beta-D-glucopyranosyl ent-16beta,17-dihydroxykauran-19-oate (1) and paniculoside IV (2). The structures of these new compounds were deduced on the basis(More)
We explored, by mutational substitutions and kinetic analysis, possible roles of the four residues involved in the hydrogen-bonding or ionic interactions found in the Ca2+-bound structure of sarcoplasmic reticulum Ca2+-ATPase, Tyr(122)-Arg(324), and Glu(123)-Arg(334) at the top part of second transmembrane helix (M2) connected to the A domain and fourth(More)
As a stable analog for ADP-sensitive phosphorylated intermediate of sarcoplasmic reticulum Ca(2+)-ATPase E1PCa(2).Mg, a complex of E1Ca(2).BeF(x), was successfully developed by addition of beryllium fluoride and Mg(2+) to the Ca(2+)-bound state, E1Ca(2). In E1Ca(2).BeF(x), most probably E1Ca(2).BeF(3)(-), two Ca(2+) are occluded at high affinity transport(More)
Four hydrolyzable tannins, 1,2,4,6-tetra-O-galloyl-β-d-glucopyranoside, 1,2,6-tri-O-galloyl-β-d-glucopyranoside, 1,4,6-tri-O-galloyl-β-d-glucopyranoside; and 1,2,4-tri-O-galloyl-β-d-glucopyranoside, along with a phenylpropanoid glucoside, syringin, were isolated from the flowers of Rafflesia kerrii. The structure elucidations were based on physical data and(More)
The possible functional abnormalities in three different Darier disease-causing Ca(2+)-ATPase (SERCA2b) mutants, Ile(274) --> Val at the lumenal end of M3, Leu(321) --> Phe on the cytoplasmic part of M4, and Met(719) --> Ile in P domain, were explored, because they exhibited nearly normal expression and localization in COS-1 cells and the high ATPase and(More)