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Investigation of anti-wear additives for synthetic esters
T. HASEGAWA,I. MINAMI,Y. KIDERA,K. HIRAO,M. MEMITA 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10
Antiwear (AW) properties of phoshphonic acid derivatives for trimethylolpropane (TMP) esters were investigated under boundary conditions. AW effect of dialkyl phosphonates depends on polarity of base fluid. They provide good AW performance in less polar TMP esters, whereas their AW effect is not sufficient in polar TMP esters. Amine sails of phosphonic acid were developed as new AW additive system for TMP esters. They provide excellent AW performance even in polar TMP esters.
Lee, Jung-Gyu,Youn, Hyung-Seop,Kang, Jung Youn,Park, Sam-Yong,Kidera, Akinori,Yoo, Yung Joon,Eom, Soo Hyun Elsevier 2018 Biochemical and biophysical research communication Vol.506 No.1
<P><B>Abstract</B></P> <P>Ubiquitin-conjugating enzymes (E2) form thioester bonds with ubiquitin (Ub), which are subsequently transferred to target proteins for cellular progress. Ube2K/E2-25K (a class II E2 enzyme) contains a C-terminal ubiquitin-associated (UBA) domain that has been suggested to control ubiquitin recognition, dimerization, or poly-ubiquitin chain formation. Ube2K is a special E2 because it synthesizes K48-linked poly-ubiquitin chains without E3 ubiquitin ligase. We found that a novel interaction between the acceptor di-Ub (Ub<SUB>2</SUB>) and the auxiliary Ube2K promotes the discharging reaction and production of tri-Ub (Ub<SUB>3</SUB>), probably by guiding and positioning the K48 (in the distal Ub) of the acceptor Ub<SUB>2</SUB> in the active site. We also determined the crystal structure of Ube2K-Ub<SUB>2</SUB> at 2.47 Å resolution. Based on our structural and biochemical data, we proposed a structural model of Ub<SUB>3</SUB> synthesis by Ube2K without E3.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The crystal structure of the Ube2K-Ub<SUB>2</SUB> complex was determined at a 2.47 Å resolution. </LI> <LI> A novel interaction between the acceptor Ub<SUB>2</SUB> and the auxiliary Ube2K was observed. </LI> <LI> Auxiliary Ube2K promotes the discharging reaction and production of Ub<SUB>3</SUB>. </LI> <LI> We propose a structural model of the Ub<SUB>3</SUB> synthesis by Ube2K. </LI> </UL> </P>
Kaori Shoji,Kaori Shoji,Masanobu Tsubaki,Yuzuru Yamazoe,Takao Satou,Tatsuki Itoh,Yasuhiro Kidera,Yoshihiro Tanimori,Masashi Yanae,Hideaki Matsuda,Atsushi Taga,Haruyuki Nakamura,Shozo Nishida 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.3
Mangiferin, 1,3,6,7-tetrahydroxyxanthone-C2-β-D-glucoside (C-glucosylxanthone), is a xanthone derivative that is widely distributed in higher plants. Recently, mangiferin was found to exhibit potential antitumor effects. However, the molecular mechanisms of this effect have not been elucidated. In the present study, we attempt to clarify the mechanism of mangiferininduced apoptosis in the human acute myeloid leukemia cell line HL-60; mangiferin was found to induce apoptosis. We also observed a concurrent increase in caspase-3 activity and DNA fragmentation. Furthermore, on examining the survival signals expressed during apoptotic induction, we observed that mangiferin caused a remarkable decrease in the nuclear entry of NF-κB p65. However, there were no changes in the expression of other survival signals,such as extracellular signal-regulated kinase 1/2, protein kinase B, and p38 mitogenactivated protein kinase. In addition, mangiferin suppressed the expressions of Bcl-xL and XIAP; however, we did not note any changes in the levels of Bcl-2, Bax, and Bim. These results indicate that mangiferin induces apoptosis by suppressing NF-κB activation and expressions of Bcl-xL and XAIP. These findings suggest that mangiferin may be useful as an anticancer agent and can be used in combination therapy with other anticancer drugs for the treatment of acute myeloid leukemia.