Browsing by Author "Yang, Ming-Chi"

Now showing 1 - 6 of 6

Crystal structure of a secondary vitamin D(3) binding site of milk beta-lactoglobulin
(2008-05-15)
Yang, Ming-Chi
;
Guan, Hong-Hsiang
;
Liu, Ming-Yih
;
Lin, Yih-Hung
;
Yang, Jinn-Moon
beta-lactoglobulin (beta-LG), one of the most investigated proteins, is a major bovine milk protein with a predominantly beta structure. The structural function of the only alpha-helix with three turns at the C-terminus is unknown. Vitamin D(3) binds to the central calyx formed by the beta-strands. Whether there are two vitamin D binding-sites in each beta-LG molecule has been a subject of controversy. Here, we report a second vitamin D(3) binding site identified by synchrotron X-ray diffraction (at 2.4 angstrom resolution). In the central calyx binding mode, the aliphatic tail of vitamin D(3) clearly inserts into the binding cavity, where the 3-OH group of vitamin D(3) binds externally. The electron density map suggests that the 3-OH group interacts with the carbonyl of Lys-60 forming a hydrogen bond (2.97 angstrom). The second binding site, however, is near the surface at the C-terminus (residues 136-149) containing part of an a-helix and a beta-strand I with 17.91 angstrom in length, while the span of vitamin D(3) is about 12.51 angstrom. A remarkable feature of the second exosite is that it combines an amphipathic alpha-helix providing nonpolar residues (Phe-136, Ala-139, and Leu-140) and a beta-strand providing a nonpolar (Ile-147) and a buried polar residue (Arg-148). They are linked by a hydrophobic loop (Ala-142, Leu-143, Pro-144, and Met-145). Thus, the binding pocket furnishes strong hydrophobic force to stabilize vitamin D(3) binding. This finding provides a new insight into the interaction between vitamin D(3) and beta-LG, in which the exosite may provide another route for the transport of vitamin D(3) in vitamin D(3) fortified dairy products. Atomic coordinates for the crystal structure Of beta-LG-vitamin D(3) complex described in this work have been deposited in the PDB (access code 2GJ5).
Haemoglobin-induced oxidative stress is associated with both endogenous peroxidase activity and H(2)O(2) generation from polyunsaturated fatty acids
(2011-03-01)
Cheng, Tsai-Mu
;
Mao, Simon J. T.
;
Lai, Shiau-Ting
;
Chang, Chia-Ching
;
Yang, Ming-Chi
Patients with increased haemolytic haemoglobin (Hb) have 10-20-times greater incidence of cardiovascular mortality. The objective of this study was to evaluate the role of Hb peroxidase activity in LDL oxidation. The role of Hb in lipid peroxidation, H(2)O(2) generation and intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was assessed using NaN(3), a peroxidase inhibitor, catalase, a H(2)O(2) decomposing enzyme and human umbilical vein endothelial cells (HUVECs), respectively. Hb induced H(2)O(2) production by reacting with LDL, linoleate and cell membrane lipid extracts. Hb-induced LDL oxidation was inhibited by NaN(3) and catalase. Furthermore, Hb stimulated ICAM-1 and VCAM-1 expression, which was inhibited by the antioxidant, probucol. Thus, the present study suggests that the peroxidase activity of Hb produces atherogenic, oxidized LDL and oxidized polyunsaturated fatty acids (PUFAs) in the cell membrane and reactive oxygen species (ROS) formation mediated Hb-induced ICAM-1 and VCAM-1 expression.
Haemoglobin-induced oxidative stress is associated with both endogenous peroxidase activity and H2O2 generation from polyunsaturated fatty acids
(2011-03-01)
Cheng, Tsai-Mu
;
Mao, Simon J. T.
;
Lai, Shiau-Ting
;
Chang, Chia-Ching
;
Yang, Ming-Chi
Patients with increased haemolytic haemoglobin (Hb) have 10-20-times greater incidence of cardiovascular mortality. The objective of this study was to evaluate the role of Hb peroxidase activity in LDL oxidation. The role of Hb in lipid peroxidation, H2O2 generation and intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was assessed using NaN3, a peroxidase inhibitor, catalase, a H2O2 decomposing enzyme and human umbilical vein endothelial cells (HUVECs), respectively. Hb induced H2O2 production by reacting with LDL, linoleate and cell membrane lipid extracts. Hb-induced LDL oxidation was inhibited by NaN3 and catalase. Furthermore, Hb stimulated ICAM-1 and VCAM-1 expression, which was inhibited by the antioxidant, probucol. Thus, the present study suggests that the peroxidase activity of Hb produces atherogenic, oxidized LDL and oxidized polyunsaturated fatty acids (PUFAs) in the cell membrane and reactive oxygen species (ROS) formation mediated Hb-induced ICAM-1 and VCAM-1 expression.
Rational crystallization of beta -lactoglobulin and vitamin D-3 complex reveal a secondary binding site
(2008-01-01)
Chen, Chun-Jung
;
Guan, Hong-Hsiang
;
Yang, Ming-Chi
;
Moo, Simon J. T.
;
生物科技學系
Single domain antibody against carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) inhibits proliferation, migration, invasion and angiogenesis of pancreatic cancer cells
(2014-03-01)
Cheng, Tsai-Mu
;
Murad, Yanal M.
;
Chang, Chia-Ching
;
Yang, Ming-Chi
;
Baral, Toya Nath
Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is over-expressed in pancreatic cancer cells, and it is associated with the progression of pancreatic cancer. We tested a single domain antibody (sdAb) targeting CEACAM6, 2A3, which was isolated previously from a llama immune library, and an Fc conjugated version of this sdAb, to determine how they affect the pancreatic cancer cell line BxPC3. We also compared the effects of the antibodies to gemcitabine. Gemcitabine and 2A3 slowed down cancer cell proliferation. However, only 2A3 retarded cancer cell invasion, angiogenesis within the cancer mass and BxPC3 cell MMP-9 activity, three features important for tumour growth and metas- tasis. The IC(50)s for 2A3, 2A3-Fc and gemcitabine were determined as 6.5 mu M, 8 mu M and 12 nM, respectively. While the 2A3 antibody inhibited MMP-9 activity by 33% compared to non-treated control cells, gemcitabine failed to inhibit MMP-9 activity. Moreover, 2A3 and 2A3-Fc inhibited invasion of BxPC3 by 73% compared to non-treated cells. When conditioned media that were produced using 2A3- or 2A3-Fc-treated BxPC3 cells were used in a capillary formation assay, the capillary length was reduced by 21% and 49%, respectively. Therefore 2A3 is an ideal candidate for treating tumours that over-express CEACAM6. (C) 2012 Elsevier Ltd. All rights reserved.
Structure of a Secondary Vitamin D-3 Binding Site of Milk beta-Lactoglobulin for Vitamin D Transport.
(2009-01-01)
Chen, Chun-Jung
;
Yang, Ming-Chi
;
Guan, Hong-Hsiang
;
Yang, Jinn-Moon
;
Chen, Wen-Liang