Mechanistic evaluation of a nucleoside tetraphosphate with a thymidylyltransferase

Rhamnose-Containing Compounds: Biosynthesis and Applications

Rhamnose-associated molecules are attracting attention because they are present in bacteria but not mammals, making them potentially useful as antibacterial agents. Additionally, they are also valuable for tumor immunotherapy. Thus, studies on the functions and biosynthetic pathways of rhamnose-containing compounds are in progress. In this paper, studies on the biosynthetic pathways of three rhamnose donors, i.e., deoxythymidinediphosphate-L-rhamnose (dTDP-Rha), uridine diphosphate-rhamnose (UDP-Rha), and guanosine diphosphate rhamnose (GDP-Rha), are firstly reviewed, together with the functions and crystal structures of those associated enzymes. Among them, dTDP-Rha is the most common rhamnose donor, and four enzymes, including glucose-1-phosphate thymidylyltransferase RmlA, dTDP-Glc-4,6-dehydratase RmlB, dTDP-4-keto-6-deoxy-Glc-3,5-epimerase RmlC, and dTDP-4-keto-Rha reductase RmlD, are involved in its biosynthesis. Secondly, several known rhamnosyltransferases from Geobacillus stearothermophilus, Saccharopolyspora spinosa, Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Streptococcus pneumoniae are discussed. In these studies, however, the functions of rhamnosyltransferases were verified by employing gene knockout and radiolabeled substrates, which were almost impossible to obtain and characterize the products of enzymatic reactions. Finally, the application of rhamnose-containing compounds in disease treatments is briefly described.

Synthesis of Nucleoside-5'-O-Tetraphosphates from Activated Trimetaphosphate and Nucleoside-5'-O-Monophosphates

This article describes a straight-forward chemical method for the synthesis of nucleoside-5'-O-tetraphosphates, such as cytosine-, guanosine-, adenosine-, and uridine-5'-O-tetraphosphates, starting from the corresponding nucleoside monophosphates and trimetaphosphate, a readily available and inexpensive starting material. The procedure involves reacting the tri(tetrabutylammonium) salt of trimetaphosphate with mesitylenesulfonyl chloride and N-methylimidazole. The resulting activated cyclic trimetaphosphate is reacted with the tetrabutylammonium salts of nucleoside monophosphates. After quenching the reaction with buffer and high-performance liquid chromatography purification, the desired nucleoside-5'-O-tetraphosphates were obtained in yields of 84% to 86%. © 2018 by John Wiley & Sons, Inc.

Investigations into the binding of jadomycin DS to human topoisomerase IIβ by WaterLOGSY NMR spectroscopy

First evidence that jadomycins bind human topoisomerase IIβ.