Yonghui Liu

A Safe and Facile Route to Imidazole-1-sulfonyl Azide as a Diazotransfer Reagent

A facile approach to the diazotransfer reagent of imidazole-1-sulfonyl azide was reported. The procedure was well optimized to clarify potential explosion risks. A high production yield as well as small batch variation was achieved even without careful pretreatment of reagents and solvents. HPLC and NMR methods to monitor the process were provided. These features made this protocol suitable for large scale preparation in academia and industry as well.

Total Synthesis of Anticoagulant Pentasaccharide Fondaparinux

The anticoagulant pentasaccharide fondaparinux was synthesized using an improved and optimized synthetic strategy including a convergent [3+2] coupling approach, orthogonal protecting groups and various glycosyl donors. The new methods of glycosylation were also used for controlling the stereochemical configuration and improving the yield of the glycosylation. In addition, HPLC and NMR methods to monitor the process of total synthesis of fondaparinux were employed. This work provides a comprehensive elaboration for the synthesis and analysis of fondaparinux based on related literature, as well as abundant information for the synthesis of heparin‐like oligosaccharides.

Graphical method for assigning Raman peaks of radial breathing modes of single-wall carbon nanotubes

In order to assign Raman scattering peaks of radial breathing modes (RBMs) of single-wall carbon nanotubes (SWNTs), we have already developed a graphical method. Two charts were constructed based on the data of diameters, RBM frequencies and electronic density of states (DOS) of SWNTs. Using them we have successfully assigned resonant scattering peaks of RBM in the Raman Spectra recorded by Rao et al. The assignments indicate that SWNT samples exhibit many different structures with no one species dominating.

A highly efficient galactokinase from Bifidobacterium infantis with broad substrate specificity.

Galactokinase (GalK), particularly GalK from Escherichia coli, has been widely employed for the synthesis of sugar-1-phosphates. In this study, a GalK from Bifidobacterium infantis ATCC 15697 (BiGalK) was cloned and over-expressed with a yield of over 80 mg/L cell cultures. The k(cat)/K(m) value of recombinant BiGalK toward galactose (164 s(-1) mM(-1)) is 296 times higher than that of GalK from E. coli, indicating that BiGalK is much more efficient in the phosphorylation of galactose. The enzyme also exhibits activity toward galacturonic acid, which has never been observed on other wild type GalKs. Further activity assays showed that BiGalK has broad substrate specificity toward both sugars and phosphate donors. These features make BiGalK an attractive candidate for the large scale preparation of galactose-1-phosphate and derivatives.