Related Articles19F NMR ligand perturbation studies on 6,7-bis(trifluoromethyl)-8-ribityllumazine-7-hydrates and the lumazine synthase complex of Bacillus subtilis. Site-directed mutagenesis changes the mechanism and the stereoselectivity of the catalyzed haloform-type reaction.
J Org Chem. 2001 Jun 1;66(11):3811-9
Authors: Scheuring J, Kugelbrey K, Weinkauf S, Cushman M, Bacher A, Fischer M
The riboflavin synthase/lumazine synthase complex of Bacillus subtilis catalyzes the last two steps in riboflavin biosynthesis. The protein comprises a capsid of 60 beta subunits with lumazine synthase activity and a core of three alpha subunits with riboflavin synthase activity. The beta subunits catalyze the formation of 6,7-dimethyl-8-ribityllumazine (3) from 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione (1) and 3,4-dihydroxy-2-butanone 4-phosphate (2). Complexes of recombinant lumazine synthase (beta(60) capsids) with 6-trifluoromethyl-7-oxo-8-ribityllumazine (10) as well as 7S- or 7R-6,7-bistrifluoromethyl-8-ribityllumazine hydrate (11) were studied by (19)F NMR spectroscopy. Despite the large molecular weight of approximately 960 kDa of the protein, spectra with separated signals of free and bound ligand could be obtained. An unusually large shift difference of 8 ppm was observed between the 7-trifluoromethyl signals of free and bound ligand for epimer B of 11 and the enzyme. The signal is sensitive to the replacement of amino acid residues F22 and H88. Lumazine synthase catalyzes the elimination of the 7-trifluoromethyl group of R-diastereomer epimer A in a haloform-like reaction. The elimination reaction is also catalyzed by F22 mutants. The H88R mutant displays an opposite stereoselectivity for epimer B and a greatly enhanced reaction rate. From a model of the epimers in the active site of the protein, the main function of the side chain of F22 seems to be to keep the substrate ring in the correct position. H88 is in a position suited to act as proton acceptor in both the physiological as well as the haloform reaction. A different mechanism of the haloform-reaction is proposed in the case of the H88R mutant, initiated by hydrogen bonding of the 7-trifluorormethyl group and the guanidinium group of the arginine residue.
Conformational Study of 9-Dehydro-9-Trifluoromethyl Cinchona Alkaloids via 19F NMR Spectroscopy: Emergence of Trifluoromethyl Moiety as a Conformational Stabilizer and a Probe
Conformational Study of 9-Dehydro-9-Trifluoromethyl Cinchona Alkaloids via 19F NMR Spectroscopy: Emergence of Trifluoromethyl Moiety as a Conformational Stabilizer and a Probe
G. K. Surya Prakash, Fang Wang, Chuanfa Ni, Jingguo Shen, Ralf Haiges, Andrei K. Yudin, Thomas Mathew and George A. Olah
http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/0/jacsat.ahead-of-print/ja202373d/aop/images/medium/ja-2011-02373d_0006.gif
Journal of the American Chemical Society
DOI: 10.1021/ja202373d
http://feeds.feedburner.com/~ff/acs/jacsat?d=yIl2AUoC8zA...
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[NMR paper] NMR studies of protein-ligand interactions.
NMR studies of protein-ligand interactions.
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Methods Mol Biol. 2005;305:197-214
Authors: Maurer T
Interaction between biological macromolecules or of macromolecules with low-molecular-weight ligands is a central paradigm in the understanding of function in biological systems. It is also the major goal in pharmaceutical research to find and optimize ligands that modulate the function of biological macromolecules. Both technological advances and new methods in the field of nuclear...
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[NMR paper] NMR and MD studies on the interaction between ligand peptides and alpha-bungarotoxin.
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J Mol Biol. 2004 Jun 18;339(5):1169-77
Authors: Bernini A, Ciutti A, Spiga O, Scarselli M, Klein S, Vannetti S, Bracci L, Lozzi L, Lelli B, Falciani C, Neri P, Niccolai N
The interaction between alpha-bungarotoxin and linear synthetic peptides, mimotope of the nicotinic acetylcholine receptor binding site, has been characterised extensively by several...
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[NMR paper] Studies of protein-ligand interactions by NMR.
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Biochem Soc Trans. 2003 Oct;31(Pt 5):1006-9
Authors: Clarkson J, Campbell ID
Solution-state NMR has become an accepted method for studying the structure of small proteins in solution. This has resulted in over 3000 NMR-based co-ordinate sets being deposited in the Protein Databank. It is becoming increasingly apparent, however, that NMR is also a very powerful tool for accessing interactions between macromolecules and various ligands....
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[NMR paper] Studies of protein-ligand interactions by NMR.
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Methods Mol Biol. 1997;60:195-232
Authors: Craik DJ, Wilce JA
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[NMR paper] Studies of protein-ligand interactions by NMR.
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Methods Mol Biol. 1997;60:195-232
Authors: Craik DJ, Wilce JA
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[NMR paper] NMR structural studies of the tight complex between a trifluoromethyl ketone inhibito
NMR structural studies of the tight complex between a trifluoromethyl ketone inhibitor and the 85-kDa human phospholipase A2.
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Biochemistry. 1993 Nov 30;32(47):12560-5
Authors: Trimble LA, Street IP, Perrier H, Tremblay NM, Weech PK, Bernstein MA
Arachidonyl trifluoromethyl ketone (AACOCF3) is a slow- and tight-binding inhibitor of the human cytosolic phospholipase A2 (cPLA2) . 19F and 13C NMR...
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[NMR paper] 13C and 15N NMR studies on the interaction between 6,7-dimethyl-8-ribityllumazine and
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Biochemistry. 1990 Feb 20;29(7):1823-8
Authors: Vervoort J, O'Kane DJ, Müller F, Bacher A, Strobl G, Lee J
The interaction between the prosthetic group 6,7-dimethyl-8-(1'-D-ribityl)lumazine and the lumazine apoproteins from two marine bioluminescent bacteria, one from a relatively thermophilic species, Photobacterium...