Browsing by Author "Li, Chen-Wei"

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Identification of Pseudomonas aeruginosa using functional magnetic nanoparticle-based affinity capture combined with MALDI MS analysis
(2009)
Liu, Jr-Chi
;
Chen, Wei-Jen
;
Li, Chen-Wei
;
Mong, Kwok-Kong Tony
;
Tsai, Pei-Jane
PA-IL is a galactophilic lectin that is found on the outer membrane of Pseudomonas aeruginosa. Pigeon ovalbumin (POA), a phosphoprotein, contains high levels of terminal Gala(1 -> 4) Gal units. Thus, magnetic nanoparticles with immobilized POA can be used as affinity probes for P. aeruginosa, functioning via the recognition of galactophilic PA-IL. We fabricated POA-bound nanoparticles (NPs) by immobilizing POA onto the surface of core/shell magnetic iron oxide/alumina NPs via metal phosphate chelation. We then used the generated NPs to probe target bacteria from complex samples. The trapped bacterial cells were characterized based on their mass peak profiles obtained from MALDI MS analyses. In addition, we confirmed the determination of P. aeruginosa using a proteomic strategy: combining the resultant MALDI MS/MS spectra of its tryptic digest with protein database searching. The feasibility of using this approach to rapidly characterize P. aeruginosa from clinical samples without the need to perform culturing steps was also demonstrated.
Low-Concentration 1,2-trans beta-Selective Glycosylation Strategy and Its Applications in Oligosaccharide Synthesis
(2009)
Chao, Chin-Sheng
;
Li, Chen-Wei
;
Chen, Min-Chun
;
Chang, Shih-Sheng
;
Mong, Kwok-Kong Tony
This study develops an operationally easy, efficient, and general 1,2-trans beta-selective glycosylation reaction that proceeds in the absence of a C2 acyl function. This process employs chemically stable thioglycosyl donors and low substrate concentrations to achieve excellent beta-selectivities in glycosylation reactions. This method is widely applicable to a range of glycosylsubstrates irrespective of their structures and hydroxyl-protecting functions. This low-concentration 1,2-trans beta-selective glycosylation in carbohydrate chemistry removes the restriction of using highly reactive thioglycosides to construct 1,2-trans beta-glycosidic bonds. This is beneficial to the design of new strategies for oligosaccharide synthesis, as illustrated in the preparation of the biologically relevant beta-(1 -> 6)-glucan trisaccharide, beta-linked Gb(3) and isoGb(3) derivatives.
Synthesis of Oligomeric Mannosides and Their Structure-Binding Relationship with Concanavalin A
(2014-07-01)
Li, Chen-Wei
;
Hon, Kai-Wei
;
Ghosh, Bhaswati
;
Li, Po-Han
;
Lin, Hsien-Ya
Small glycodendrimers with a-mannosyl ligands were synthesized by using copper-catalyzed azide-alkyne coupling chemistry and some of these molecules were used as multivalent ligands to study the induction of concanavalin A (Con A) precipitation. The results showed that the monovalent mannose ligand could induce the precipitation of Con A. This unexpected finding initiated a series of studies to characterize the molecular basis of the ligand-lectin interaction. The atypical precipitation is found to be specific to the mannose, fluorescein moiety (FITC), and Con A. Apparently the mannose ligand binds to Con A through hydrogen-bonding interactions, whereas the binding of FITC is mediated by hydrophobic forces.