32,826 research outputs found
Mu Tao Chang, viola and Ya Lin Huang, piano, April 23, 2016
Full text linkThis is the concert program of the Mu Tao Chang, viola and Ya Lin Huang, piano performance on Saturday, April 23, 2016 at 2:30 p.m., at the Marshall Room, 855 Commonwealth Avenue. Works performed were Sonata No. 2 in E-flat for viola and piano, Op. 120 by Johannes Brahms, Cello Suite No. 6 by Johann Sebastian Bach, and Viola Concerto by Béla Bartók. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund
Mu-Tao Chang, viola and Ya-Lin Huang, piano, March 24, 2016
Full text linkThis is the concert program of the Mu-Tao Chang, viola and Ya-Lin Huang, piano performance on Friday, March 24, 2017 at 6:30 p.m., at the Marshall Room, 855 COmmonwealth Avenue. Works performed were Sonata No. 1 for Viola and Piano, H355 by Bohuslav Martinu, Sonata for Viola and Piano, Op. 11-4 by Paul Hindemith, and Rhapsody-Concerto for Viola and Orchestra by B. Martinu. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund
The political role of the people's liberation army 1949-1973
Full text linkThis thesis is to study the political role of the People's Liberation Army from the approach of structure and function. The framework of the thesis consists of three major parts, first, the influence of Chinese traditional political culture on, and the formation of, the political role of the PL A; second, the influence of domestic political struggles and external military conflicts on the development of the political role of the PLA; and the third, the analysis of the transition of the PLA's political role from the structure and personnel arrangements of the CCPCC Within the above-mentioned three scopes, this thesis make a thorough discussion on the following: (1) The relationship between the structure of the PRC and the formation of the PLA's political role; (2) How has ideology influenced the army's political role; (3) What is Mao's viewpoint and his influence on the development of the army's political role; (4) What is the link between the army and the party, and how has this developed; (6) What accounts for the expansion of the PLA's political functions; (7) What is the influence of political factional struggles on the PLA's political role; (8) Is it political institution or military institution that controls the recruitment of the military elite; (9) What are the disparities between the military elite in handling international conflicts and what are their political considerations; (10) What is the Party's position in the army; (11) How have the Party’s important meetings and personnel arrangements influenced the rise and fall of the PLA's political role
Data supporting the results in the paper: Sheng-Hsin Su, Biing T. Guan, Chia-Hao Chang-Yang, I-Fang Sun, Hsiang-Hua Wang, Chang-Fu Hsieh. In press. "Multi-stemming and size enhance survival of dominant tree species in a frequently typhoon-disturbed forest". Journal of Vegetation Science.
No full textData supporting the results in the paper:Sheng-Hsin Su, Biing T. Guan, Chia-Hao Chang-Yang, I-Fang Sun, Hsiang-Hua Wang, Chang-Fu Hsieh. In press. "Multi-stemming and size enhance survival of dominant tree species in a frequently typhoon-disturbed forest". Journal of Vegetation Science. https://doi.org/10.1111/jvs.12858</div
Sinocyrtaspis angustisulca Chang, Bian & Shi 2012
No full textSinocyrtaspis angustisulca Chang, Bian & Shi, 2012 (Fig. 4, Map 1) Sinocyrtaspis angustisulcus Chang Bian & Shi, 2012, Zootaxa, 3495: 85. Holotype: male; type locality: Badagongshan, Sangzhi, Hunan; location of type specimen: the Museum of Hebei University. Male of this species was also reported by Chang et al. (2012). The original description and photographs are very clear. Description of Female. Anterior margin of pronotum almost straight while posterior margin arc-shaped and metazona not raised; lateral lobe slightly narrow at metazona, humeral sinus absent (Fig. 4B). Posterior margin of 9th abdominal tergite arc-shaped concave, lateral margins extending posteriorly. 10th abdominal tergite somewhat prolonged posteriorly, faintly concave on posterior margin (Fig. 4E). Cercus conical, apex obtusely rounded. Ovipositor moderately bent dorsad, basal area robust and apex acute, dorsal and ventral margins smooth (Fig. 4C, F). Subgenital plate slightly trapezoidal, concave dorsally in the midline, narrow at apex, posterior margin gently concave (Fig. 4D). Coloration. Body yellowish brown, green when alive. Lateral margins of disc of pronotum with 1 longitudinal blackish brown stripe respectively and dorsal surface of abdomen with 1 longitudinal light brown stripe in the midline. All claws and apices of dorsal spines of hind tibiae blackish brown. All tarsi green. This is the first description of a female of the species. Measurements (mm). Body: ♀ 10.5–11.3; pronotum: ♀ 4.2–4.5; hind femora: ♀ 9.0–9.3; ovipositor: 6.1–6.2. Material examined. Holotype: ♂, Badagongshan, Sangzhi, Hunan, China, 14 August, 2011, coll. Fuming Shi. Other specimens: 1♂, Doupengshan, Badagongshan, Hunan, 10 October, 2014, coll. Jianhua Huang; 4♂, Badagongshan, Sangzhi, Hunan, 9 August, 2018, coll. Tao Wang; 6♂ 3♀, Badagongshan, Sangzhi, Hunan, 10 August, 2018, coll. Tao Wang; 1♂, Badagongshan, Sangzhi, Hunan, 11 August, 2018, coll. Tao Wang. Distribution. China (Hunan). Discussion. Female of Sinocyrtaspis angustisulca Chang, Bian & Shi, 2012 is of basic similar shape with females of S. spina Shi & Du, 2006 and S. brachycerca Chang, Bian & Shi, 2012, but differs in posterior margin of 10th abdominal tergite slightly concave, subgenital plate trapezoidal, concave dorsad in the midline, apical area narrow, posterior margin faintly concave in the middle.Published as part of Wang, Tao, Shi, Fuming & Chang, Yanlin, 2019, Revision of the genus Sinocyrtaspis Liu, 2000 (Orthoptera: Tettigoniidae: Meconematinae), pp. 127-138 in Zootaxa 4609 (1) on pages 132-133, DOI: 10.11646/zootaxa.4609.1.5, http://zenodo.org/record/315095
JOP822157_supplemental_material – Supplemental material for Effect of N-methyl-D-aspartate-receptor-enhancing agents on cognition in patients with schizophrenia: A systematic review and meta-analysis of double-blind randomised controlled trials
No full textSupplemental material, JOP822157_supplemental_material for Effect of N-methyl-D-aspartate-receptor-enhancing agents on cognition in patients with schizophrenia: A systematic review and meta-analysis of double-blind randomised controlled trials by Chun-Hung Chang, Hsien-Yuan Lane, Ping-Tao Tseng, Shaw-Ji Chen, Chieh-Yu Liu and Chieh-Hsin Lin in Journal of Psychopharmacology</p
Pseudophlugiolopsis bitubera gen. nov., sp. nov. and a new species of Allicyrtaspis Shi, Bian & Chang, 2013 (Tettigoniidae: Meconematinae: Meconematini) from China
No full textWang, Tao, Zhou, Zhijun, Chang, Yanlin (2020): Pseudophlugiolopsis bitubera gen. nov., sp. nov. and a new species of Allicyrtaspis Shi, Bian & Chang, 2013 (Tettigoniidae: Meconematinae: Meconematini) from China. Zootaxa 4802 (1): 182-188, DOI: https://doi.org/10.11646/zootaxa.4802.1.1
Structural and Functional Studies of Type-III geranylgeranyl Pyrophosphate Synthase from Saccharomyces cerevisiae
No full text類異戊二烯族 (isoprenoid) 為廣泛分布於自然界中的化合物，由一類異戊二烯轉移酵素 (trans-prenyl transferase) 所催化合成，並且亦是以異戊二烯焦磷酸 (isopentenyl pyrophosphate) 為骨架所構成的聚合物。本研究之酵母菌第三型－四異戊二烯焦磷酸合成酵素 (geranylgeranyl pyrophosphate synthase) 可催化一個異戊二烯焦磷酸與法呢基焦磷酸 (farnesyl pyrophosphate) 反應產生四異戊二烯焦磷酸 (geranylgeranyl pyrophosphate)，此產物是四異戊二烯化 (geranylgeranylated)蛋白質、胡蘿蔔素 (carotenoid)、細胞膜脂質等－這些在生物體內重要分子的前趨物。不過藉由不同的一類異戊二烯轉移酵素，所合成出長度具多樣性的直鏈產物，分別在生物體內亦扮演不同的生理角色，因此此群酵素必須非常精準地調控其直鏈產物的長短。但是酵母菌第三型－四異戊二烯焦磷酸合成酵素不論從胺基酸系列比對，還是以已知結構的法呢基焦磷酸合成酵素為藍圖，皆無法推論出其可能調控直鏈產物的機制，而此即為本論文探討重點之一；此外，近年已有文獻報導以此纇酵素作為治療癌症的重要標的物之一。在本論文中，首度解出此酵素立體結構，為兩個相同單元體 (monomer) 所組成的二聚體 (dimer)，每一個單元體由15個α螺旋 (helix) 並以環狀物 (loop) 所連接構成，其催化中心由兩個DDXXD motif所構成；同時意外發現鎂離子和活性中心兩個重要的胺基酸形成配位鍵，之後藉由動力學與螢光光譜的分析，證實鎂離子在催化反應中的聚合反應(condensation reaction) 扮演重要角色，而似乎不影響受質和酵素的親合。然於過去的研究中，指出合成約10到25碳數的短碳鏈一類異戊二烯轉移酵素，利用位於第一個DDXXD motif前面第四或第五個的芳香族胺基酸來調控其直鏈產物的長短；不過自胺基酸序列的比對中，卻發現第三型－四異戊二烯焦磷酸合成酵素沒有此特徵。因此利用酵素立體結構與定點突變，對調控產物鏈長之反應機制做進一步的探討，由研究結果證實第三型－四異戊二烯焦磷酸合成酵素的產物鏈長由Tyr107和His108這兩個重要殘基來調控。在立體結構的比較中，發現酵母菌第三型－四異戊二烯焦磷酸合成酵素其N端第一個α螺旋和之後的環狀物，其構形與方向和其他一類異戊二烯轉移酵素相異；而兩個單體間界面 (interface) 的高度保留殘基，為不具有極性的胺基酸Met111和也和多數一類異戊二烯轉移酵素利用芳香族胺基酸的π-π交互作用促進二元體的形成機制不同。本論文證實酵素N端的結構和兩個單體間界面共同決定二元體的形成；但為何具有與二元體相同活性區域的單元體，會失去酵素活性? 因此利用定點突變製造與無活性單元體△(1–17)，擁有相同螢光的特質但保留活性的二聚體W15F做進一步的探討，之後再由螢光光譜分析和阻流反應分析儀 (stopped-floe) 來分析兩者之間的差異，自結果可初步推論單元體似乎仍具有與受質的結合能力但無法進行催化反應中的聚合反應；亦自實驗中發現酵母菌第三型－四異戊二烯焦磷酸合成酵素和兩個不同受質－異戊二烯焦磷酸和法呢基焦磷酸－的結合沒有先後順序。最後希望藉由本研究，對酵母菌第三型－四異戊二烯焦磷酸合成酵素在立體結構、反應機制和動力學有進一步的了解。Geranylgeranyl pyrophosphate synthase (GGPPs) catalyzes the condensation reaction of farnesyl pyrophosphate (FPP) with isopentenyl pyrophosphate (IPP) to generate C20 geranylgeranyl pyrophosphate, which is a precursor for carotenoids, chlorophylls, geranylgeranylated proteins, and archaeal ether linked lipid. For short-chain trans-prenyltransferases synthesizing C10–C25 products, bulky residues generally occupy the 4th or 5th position upstream from the first DDXXD motif to block further elongation of the final products. However, type-III GGPPs in eukaryotes lack any large residue at these positions. In this study, the first structure of homodimeric type-III GGPPs from Saccharomyces cerevisiae has been determined to 1.98-Å resolution. Each subunit is composed of 15 alpha-helices joined by connecting loops and is arranged with alpha-helices around a large central cavity. An elongated hydrophobic crevice surrounded by D, F, G, H, and I alpha-helices contains two DDXXD motifs at the top for substrate binding with one Mg2+ coordinated by Asp75, Asp79, and four water molecules. It is sealed at the bottom with three large residues of Tyr107, Phe108, and His139. Compared to the major product C30 synthesized by mutant H139A, the products generated by mutant Y107A and F108A are predominantly C40 and C30, respectively, suggesting the most important role of Tyr107 in determining the product chain length.
Distinct from other known structures of trans-prenyltransferases, the N-terminal 17 amino acids (9-amino acid helix A and the following loop) of the yeast GGPPs protrude from the helix core into the other subunit and contribute to the tight dimer formation. Deletion of the first 9 or 17 amino acids caused the dissociation of dimer into monomer and these two mutants of △(1–9) and △(1–17) showed a 300-fold decrease and abolished in enzyme activity, respectively. Unlike other trans-prenyltransferases usingπ-πstacking interactions to form dimer, we also identified Met111 residue on the highly conserved helix F in the interface between two subunits of GGPPs to be the essential for dimer formation. Consequently, the replacement Met111 with Glu resulted in a shift form dimer to monomer for the M111E mutant enzyme and about 3.5-fold decrease in catalytic activity. The replacement of Met111 with Phe to create a hydrophobic dimer interface brought the monomeric △(1–9) mutant to a partial tetramer and 15-fold increase in catalytic activity compared with △(1–9). These results suggest the N-terminal helix and the critical residue in the interface region may both contribute to the dimer formation.
To investigate the differences in the catalytic properties between dimer and monomer, the site-directed mutagenesis, fluorescence assay, and stopped-flow experiments were performed. One of two fluorescent Trp resides in GGPPs primary sequence, Trp15, was changed to Phe to create W15F to monitor the fluorescence change of Trp148 during the substrate binding and reaction. The monomeric △(1–17) also containing Trp148 served for comparison. Similar protein intrinsic fluorescence change was observed upon addition of FPP and IPP for the W15F and △(1–17). According to this preliminary study on fluorescence spectrophotometer assay and stopped-flow experiments, the monomer without catalytic activity may lose the performance on the condensation reaction, one step of the catalytic reaction. Based on the fluorescence measurements, GGPPs bind with FPP and IPP in a random binding order. The Mg2+ concentration dependence of the catalytic rate by GGPPs shows that the activity is maximal at [Mg2+] = 5 mM, but drops significantly when [Mg2+] = 50 mM.
In summary, our results provide a thorough understanding of S. cerevisiae type-III GGPPs in its structure, mechanism and kinetics, in terms of product chain length determination, dimer formation, substrate induced protein conformational change, and the role of Mg2+ ion in catalysis.中文摘要 1
ABSTRACT 3
INTRODUCTION 6
1-1 Characteristics and Biosynthesis of Isoprenoid 7
1-2 Classification of Prenyltransferases 7
1-3 Isoprenyl Pyrophosphate Synthases 8
1-4 Mechanism of Product Determination of trans-prenyltransferases 9
1-5 Mechanism of Dimer Formation 10
1-6 Specific Aims of This Study 11
MATERIAL AND METHODS 15
2-1 Chemicals 16
2-2 Expression and Purification of GGPPs 16
2-3 Preparation of Selenomethionine-labeled GGPPs 17
2-4 Mass Spectrometry Analysis 18
2-5 Crystallization and Data Collection 18
2-6 Structure Determination and Refinement 19
2-7 Site-directed Mutagenesis of GGPPs 19
2-8 Kinetic Parameter Measurements 20
2-8-1 Kinetic Constant Measurements of Km and kcat Values 20
2-8-2 Reaction Kinetics of GGPPs under Various Concentrations of Mg2+ 21
2-9 Final Products Formation and Analysis 21
2-10 Identification of the Critical Regions for Dimer Formation 22
2-10-1 Construction of N-terminal Truncated Mutants 22
2-10-2 Gel Filtration Chromatography 23
2-10-3 Circular Dichroism (CD) Experiments 23
2-11 Probing the Substrate Binding and Conformational Changes using Trp Mutants and Substrate Analog FsPP 23
2-11-1 Fluorescence Spectrophotometer Assay 24
2-12 Stopped Flow Experiments 25
2-12-1 Measurements of Substrate Binding (kon) 25
2-12-2 Monitoring the Protein Conformational Change during Catalysis 25
RESULTS 27
3-1 Purification of wild-type, SeMet-labeled, and mutats GGPPs 28
3-2 Biochemical Analysis of Recombinant S. cerevisiae GGPPs 28
3-3 Crystal Structure of S. cerevisiae GGPPs 29
3-3-1 Overall Structure 29
3-3-2 Active Site Structure 30
3-3-3 Residues Responsible for Controlling Product Chain Length 31
3-4 Mechanism of Product Chain Length Determination 31
3-4-1 Reaction Kinetics and Final Products of Different Mutants 31
3-4-2 The Molecular Ruler Mechanism 33
3-5 Mechanism of Dimer Formation of GGPPs 34
3-5-1 The Function of N-terminal Helix A 34
3-5-2 The Function of Critical Residue in Interface 35
3-6 Probing the Substrate Binding and Conformational Change 36
3-6-1 Substrates Quench the GGPPs Intrinsic Fluorescence 36
3-6-2 Comparison of Trp Mutant and Deletion Mutant in Fluorescence Assay 37
3-6-3 Stopped-Flow Experiments 37
3-7 Role of Mg2+ Ion in Catalysis 38
3-7-1 Reaction Kinetics under Different Concentration of Mg2+ 39
3-7-2 Binding Mode Probed by Fluorescence Experiments 40
DISCUSSION 41
ACKNOWLEDGMENT 48
REFERENCES 49
TABLES 56
FIGURES 65
POSTER 99
PUBLISHED PAPER 10
David Wen-wei Chang et Richard Y. Chuang, The Politics of Hong Kong's Reversion to China
No full textHsin-Chi Kuan, Jacquet Raphaël. David Wen-wei Chang et Richard Y. Chuang, The Politics of Hong Kong's Reversion to China. In: Perspectives chinoises, n°66, 2001. pp. 90-91
Tao Xingzhi ge qu. I
No full textSide A. 1. 捧著一顆心來不帶半根草去(一)(二) ; 2. 在我的世界里小孩青年最大 ; 3. 一群小好漢(一)(二) ; 4. 追悼慈母歌 ; 5. 梅香苦 ; 6. 三代 ; 7. 朝陽歌 ; 8. 小庄晓 ; 9. 问江 ; 10. 诗的学校 ; 11. 紀念牛頓与伽利略 ; 12. 拉車 ; 13. 马克思颂 ; 14. 跟青年學 ; 15. 歌唱现代 ; 16. 寂寞 ; 17. 爱国歌 ; 18. 科学的春天 ; 19. 小小徽机真灵巧 ; 20. 玩科学把戏真有趣 ; 21. 水姑娘午曲 -- Side B. 1. 大哉陶子 ; 2. 哭陶先生 ; 3. 我是中国人 ; 4. 國民與我 ; 5. 人民教师我爱你 ; 6. 我们的青春常在 ; 7. 千教万教教人求真, 千学万学学做真人 ; 8. 我要看看世界 ; 9. 今天 ; 10. 少年 ; 11. 我的小怀抱 ; 12. 看荷花舞 ; 13. 人的体操 ; 14. 问到底 ; 15. 立大志, 求大智, 做大事 ; 16. 团结御侮文体 ; 17. 民之所好三首 ; 18. 诗人节祝词 ; 19. 只道早还乡 ; 20. 好了歌 ; 21. 中国小孩子过新年 ; 22. 教师歌 ; 23. 忠心之歌 ; 24. 我爱有趣的谈天会 (未录完).陶城曲 ; 陶城演唱 ; 杜鳴心, 陳貽鑫, 巫漪丽鋼琴演奏.Possibly reproduced from other commercial recording or radio broadcast (Pending for review)"如蘭, 學鐄教授惠存: 陶城, 陳樹新贈, 1988.8.26"--Side A.Electronic reproduction from Rulan Chao Pian Audio Cassette Collection.Composer : 陶城.Singer : 陶城 ; Piano : 杜鳴心, 陳貽鑫, 巫漪丽.Sung in Chinese.Tao Cheng qu ; Tao Cheng yan chang ; Du Mingxin, Chen Yixin, Wu Yili gang qin yan zou."Rulan, Xuehuang jiao shou hui cun: Tao Cheng, Chen Shuxin zeng, 1988.8.26"--Side A.Composer, Tao Cheng.Singer: Tao Cheng ; Piano: Du Mingxin, Chen Yixin, Wu Yili.Detailed contents in vernacular field only
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