Jia Zhen Sheng

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AIMS To determine the effects of the ratios of hyaluronan synthase expression level to precursor sugar UDP-GlcA biosynthesis ability on the molecular weight (MW) of hyaluronic acid (HA) in recombinant Lactococcus lactis. METHODS AND RESULTS The genes szHasA (hyaluronan synthase gene) and szHasB (UDP-glucose-6-dehydrogenase gene) of Streptococcus(More)
AIM This study assessed the clinical significance of incidental colorectal 2-fluoro-2-deoxyglucose (FDG) uptake using (18) F-FDG positron emission tomography/computed tomography (PET/CT) scans and evaluated the importance of colonoscopy when incidental colorectal FDG uptake was observed. METHOD A prospective study was designed and conducted at a single(More)
Nucleobase modifications dramatically alter nucleic acid structure and thermodynamics. 2-thiouridine (s(2)U) is a modified nucleobase found in tRNAs and known to stabilize U:A base pairs and destabilize U:G wobble pairs. The recently reported crystal structures of s(2)U-containing RNA duplexes do not entirely explain the mechanisms responsible for the(More)
A low-temperature atomic force microscope (cryo-AFM), operated in liquid nitrogen vapor, has been constructed for biological applications. The system provides an adjustable imaging temperature from 77 to 220 K with atomic resolution achieved on crystalline specimens. Imaging with NaCl microcrystals demonstrates that the system is free from surface(More)
It is estimated that over two thirds of all new crystal structures of proteins are determined via the protein selenium derivatization (selenomethionine (Se-Met) strategy). This selenium derivatization strategy via MAD (multi-wavelength anomalous dispersion) phasing has revolutionized protein X-ray crystallography. Through our pioneer research, similarly, Se(More)
The high-resolution structure of the DNA (5'-GTGTACA-C-3') with the selenium derivatization at the 2'-position of T2 was determined via MAD and SAD phasing. The selenium-derivatized structure (1.28 A resolution) with the 2'-Se modification in the minor groove is isomorphorous to the native structure (2.0 A). To directly compare with the conventional bromine(More)
The mixture of 2'-5' and 3'-5' linkages generated during the nonenzymatic replication of RNA has long been regarded as a central problem for the origin of the RNA world. However, we recently observed that both a ribozyme and an RNA aptamer retain considerable functionality in the presence of prebiotically plausible levels of linkage heterogeneity. To better(More)
Specificity of nucleobase pairing provides essential foundation for genetic information storage, replication, transcription and translation in all living organisms. However, the wobble base pairs, where U in RNA (or T in DNA) pairs with G instead of A, might compromise the high specificity of the base pairing. The U/G wobble pairing is ubiquitous in RNA,(More)
Selenium modification of nucleic acids is of great importance in X-ray crystal structure determination and functional study of nucleic acids. Herein, we describe a convenient synthesis of a new building block, the 2'-SeMe-modified guanosine (G(Se)) phosphoramidite, and report the first incorporation of the 2'-Se-G moiety into DNA. The X-ray crystal(More)