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639 results on '"YE, Xin-Shan"'

103. Total Synthesis of a Hyperbranched N‐Linked Hexasaccharide Attached to ATCV‐1 Major Capsid Protein without Precedent.

Author

Wang, Yong‐Shi, Wu, Yong, Xiong, De‐Cai, and Ye, Xin‐Shan

Subjects
CAPSIDS, PROTEINS, GLYCANS, CHLORELLA viruses, GLYCOSYLATION
Abstract

Summary of main observation and conclusion: The N‐glycans attached to some chloroviruses comprise a hyperbranched core structure without precedent. We are interested in the chemical synthesis of the hexasaccharide attached to ATCV‐1 (Acanthocystis turfacea Chlorella virus 1) for its distinct structure. After exploring four routes, the target hexasaccharide 2 was successfully synthesized for the first time in overall 10% yield over 8 steps from thioglycoside building blocks. This synthetic protocol is characterized by the three‐component one‐pot glycosylation and the regioselective glycosylation reactions. The disclosed synthetic approach to this new type of N‐glycans will facilitate the in‐depth understanding of their biological functions. A highly branched hexasaccharide was successfully synthesized by the three‐component preactivation‐based one‐pot glycosylation and the regioselective glycosylation reactions for the first time. [ABSTRACT FROM AUTHOR]

Published
2019
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139. Synthesis and Antigenic Evaluation of Oligosaccharide Mimics of Vi Antigen from Salmonella typhi.

Author

Zhang, Gao ‐ Lan, Yang, Lin, Zhu, Jingjing, Wei, Mengman, Yan, Wanjun, Xiong, De ‐ Cai, and Ye, Xin ‐ Shan

Subjects
SALMONELLA typhi, MICROBIAL virulence, POLYSACCHARIDES, OLIGOSACCHARIDES, TYPHOID fever, RING formation (Chemistry), PREVENTION, DISEASE risk factors
Abstract

Salmonella typhi is responsible for typhoid fever, which is a serious health threat in developing countries. As a virulent factor of Salmonella typhi, the purified Vi polysaccharide (Vi PS) has become an effective vaccine to combat typhoid fever. The chemical synthesis can provide homogeneous and well-defined molecules for the development of Vi-based vaccines. However, the synthesis of Vi oligosaccharides in high yields and with exclusive α-stereoselectivities remains very challenging. In this paper, a series of Vi pseudooligosaccharides, including pseudo tetra-, hexa-, and octa-saccharides were efficiently synthesized. These oligosaccharide analogues were conjugated by carbon chain tether through olefin cross metathesis or by the 1,2,3-triazole moiety through copper (I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC). The binding affinities of these oligosaccharide mimics to anti-Vi antibodies were investigated. These results will be beneficial to the further development of Vi-based oligosaccharide vaccines. [ABSTRACT FROM AUTHOR]

Published
2017
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146. Programmable one-pot oligosaccharide synthesis

Author

Zhang, Zhiyuan, Ollmann, Ian R., Ye, Xin-Shan, Wischnat, Ralf, Baasov, Timor, and Wong, Chi-Huey

Subjects
Oligosaccharides -- Research, Glycosides -- Analysis, Chemistry
Abstract

A study was conducted to analyze the one-pot preparation of oligosaccharides by determining the reactivity of a number of p-methylphenyl thioglycoside donors. The relative reactivities of a series of glycoside donors were quantified. A database of thioglycosides as glycosyl donors was then developed using reactivity data. In addition, the reactivity of each monomer was determined separately by defining the relative reactivity value as a relative measure of reactivity for a given monosaccharide or disaccharide.

Published
1999

147. Aminoglycoside mimetics as small-molecule drugs targeting RNA

Author

Ye Xin-Shan and Li-He Zhang

Subjects
Pharmacology, Messenger RNA, biology, Organic Chemistry, Aminoglycoside, Molecular Mimicry, Molecular Sequence Data, Ribozyme, Rational design, RNA, medicine.disease_cause, Biochemistry, Small molecule, Anti-Bacterial Agents, Molecular mimicry, Aminoglycosides, Carbohydrate Sequence, RNA, Ribosomal, Drug Discovery, biology.protein, medicine, Molecular Medicine, Antibacterial agent
Abstract

The potential of RNA as a new drug target has recently come to the fore, with the recognition that RNA molecules can adopt complex three-dimensional structures that, as with proteins, enable the design of specific ligands. Another reason for the present interest comes from the fact that many pathogenic agents, such as retroviruses, encode their genetic information in RNA strands. Unfortunately, the high toxicity and rapid emergence of high-level resistance have severely limited the usefulness of naturally occurring aminoglycoside antibiotics. To tackle these problems, it is an important concern to design new synthetic compounds with smaller, simpler structures which possess higher RNA binding affinity, better selectivity, better antibiotic activity, and stronger resistance against the aminoglycoside-modifying enzymes compared to their parent structures. Here, we will attempt a survey of current efforts to develop aminoglycoside mimetics or derivatives that target RNA. The latest advances in this field including rational design, synthetic strategy, and structure activity relationships are reviewed.

Published
2002

149. Assembly of oligosaccharide libraries with a designed building block and an efficient orthogonal protection-deprotection strategy

Author

Wong, Chi-Huey, Ye, Xin-Shan, and Zhang, Zhiyuan

Subjects
Oligosaccharides -- Research, Functions, Orthogonal -- Research, Chemistry
Abstract

An effective library approach to oligosaccharides is described using a designed building block with four selectively removable protecting groups as the core for the source of acceptors and high-yielding coupling with different donors. The monosaccharide building block with four selectively removable protecting groups was designed to demonstrate the feasibility of the strategy. Results demonstrate that an effective orthogonal strategy for the synthesis of a library of oligosaccharides as individual entities has been developed.

Published
1998

150. 3,4-didehydrothiophene: generation, trapping reactions and ab initio study

Author

Ye, Xin-Shan, Li, Wai-Kee, and Wong, Henry N.C.

Subjects
Cyclic compounds -- Research, Diels-Alder reaction -- Research, Ring formation (Chemistry) -- Research, Chemistry
Abstract

Evidence concerning the existence of 3,4-didehydrothiophene as a synthetic intermediate has been obtained. The five-membered cyclic cumulene, which was characterized using the complete-active-space self-consistent field method, was prepared from phenyl 4-(trimethylsilyl)thien-3-yl iodonium triflate which, in turn, was synthesized from 3,4-bis(trimethylsilyl)thiophene. Its existence was confirmed by the generation of its (2 + 2)- and (4 + 2)-cycloaddition adducts with dienes.

Published
1996

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