630108-93-9Relevant academic research and scientific papers
4 -THIONUCLEOTIDE
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Page/Page column 8-9, (2010/02/11)
Disclosed is a compound of formula I: [wherein B is a nucleobase selected from the group consisting of adenine, guanine, cytosine, uracil and hypoxanthine], a compound of formula II: [wherein B' is a nucleobase selected from the group consisting of adenin
Catalytic Mechanism of S-Ribosylhomocysteinase (LuxS): Direct Observation of Ketone Intermediates by 13C NMR Spectroscopy
Zhu, Jinge,Hu, Xubo,Dizin, Eric,Pei, Dehua
, p. 13379 - 13381 (2007/10/03)
S-Ribosylhomocysteinase (LuxS) catalyzes the cleavage of the thioether linkage of S-ribosylhomocysteine (SRH) to produce l-homocysteine and 4,5-dihydroxy-2,3-pentanedione (DHPD). This is a key step in the biosynthetic pathway of the type II autoinducer (AI-2) in both Gram-positive and Gram-negative bacteria. Previous studies demonstrated that LuxS contains a catalytically essential Fe2+ ion. The catalytic mechanism of LuxS was investigated using 2- and 3-13C-labeled SRH as substrate and 13C NMR spectroscopy. These studies revealed the presence of 2- and 3-keto intermediates in the catalytic pathway. The 2-keto intermediate was chemically synthesized, and its chemical and kinetic competence was demonstrated. The results support a catalytic mechanism in which the metal ion catalyzes an internal redox reaction, shifting the carbonyl group from the C-1 position to the C-3 position. Subsequent β-elimination at the C-4 and C-5 positions releases homocysteine as a free thiol. The results also suggest that Cys-84 and Glu-57 are the possible general acids/bases for proton transfer during catalysis and that the keto intermediates are released from the enzyme active site before rebinding and completion of the reaction. Copyright
