scholarly journals Uncovering the chemistry of C–C bond formation in C-nucleoside biosynthesis: crystal structure of a C-glycoside synthase/PRPP complex

2020 ◽  
Vol 56 (55) ◽  
pp. 7617-7620 ◽  
Author(s):  
Sisi Gao ◽  
Ashish Radadiya ◽  
Wenbo Li ◽  
Huanting Liu ◽  
Wen Zhu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Bond Formation ◽  
Biologically Active ◽  
X Ray

X-Ray crystal structure of a novel C-glycoside synthase involved in the biosynthesis of biologically active C-nucleosides and C-nucleotides.

scholarly journals X-ray diffraction studies of enkephalins. Crystal structure of [(4′-bromo) Phe4,Leu5]enkephalin

1984 ◽  
Vol 218 (3) ◽  
pp. 677-689 ◽  
Author(s):  
T Ishida ◽  
M Kenmotsu ◽  
Y Mino ◽  
M Inoue ◽  
T Fujiwara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Heavy Atom ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Biologically Active ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relationship Of

In order to investigate the structure-activity relationship of [Leu5]- and [Met5]enkephalins, [(4′-bromo)Phe4, Leu5]-, [(4′-bromo)Phe4, Met5]- and [Met5] enkephalins were synthesized and crystallized. The crystal structure of [(4′-bromo) Phe4, Leu5]- enkephalin was determined by X-ray diffraction method using the heavy atom method and refined to R = 0.092 by the least-squares method. The molecule in this crystal took essentially the same type I' beta-turn conformation found in [Leu5]enkephalin [Smith & Griffin (1978) Science 199, 1214-1216). On the other hand, the preliminary three-dimensional Patterson analyses showed that the most probable conformations of [(4′-bromo)Phe4,Met5]- and [Met5]enkephalins are both the dimeric extended forms. Based on these insights, the biologically active conformation of enkephalin was discussed in relation to the mu- and delta-receptors.

scholarly journals An unusual thionyl chloride-promoted C−C bond formation to obtain 4,4'-bipyrazolones

2018 ◽  
Vol 14 ◽  
pp. 1287-1292 ◽  
Author(s):  
Gernot A Eller ◽  
Gytė Vilkauskaitė ◽  
Algirdas Šačkus ◽  
Vytas Martynaitis ◽  
Ashenafi Damtew Mamuye ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Thionyl Chloride ◽  
Alkaline Hydrolysis ◽  
Bond Formation ◽  
Crystal Structure Analysis ◽  
X Ray ◽  
Spectroscopic Investigations

Dialkyl 5,5'-dioxo-4,4'-bipyrazole-4,4'-dicarboxylates are readily obtained by the reaction of 5-hydroxypyrazole-4-carboxylates in refluxing thionyl chloride. The obtained diesters can be transformed into the corresponding 4,4'-bipyrazoles via alkaline hydrolysis and subsequent decarboxylation. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a representative 5,5'-dioxo-4,4'-bipyrazole-4,4'-dicarboxylate was confirmed by X-ray crystal structure analysis.

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