47774-99-2Relevant articles and documents
Emissive Synthetic Cofactors: An Isomorphic, Isofunctional, and Responsive NAD+ Analogue
Rovira, Alexander R.,Fin, Andrea,Tor, Yitzhak
supporting information, p. 15556 - 15559 (2017/11/14)
The synthesis, photophysics, and biochemical utility of a fluorescent NAD+ analogue based on an isothiazolo[4,3-d]pyrimidine core (NtzAD+) are described. Enzymatic reactions, photophysically monitored in real time, show NtzAD+ and NtzADH to be substrates for yeast alcohol dehydrogenase and lactate dehydrogenase, respectively, with reaction rates comparable to that of the native cofactors. A drop in fluorescence is seen as NtzAD+ is converted to NtzADH, reflecting a complementary photophysical behavior to that of the native NAD+/NADH. NtzAD+ and NtzADH serve as substrates for NADase, which selectively cleaves the nicotinamide's glycosidic bond yielding tzADP-ribose. NtzAD+ also serves as a substrate for ribosyl transferases, including human adenosine ribosyl transferase 5 (ART5) and Cholera toxin subunit A (CTA), which hydrolyze the nicotinamide and transfer tzADP-ribose to an arginine analogue, respectively. These reactions can be monitored by fluorescence spectroscopy, in stark contrast to the corresponding processes with the nonemissive NAD+.
Transition state structure of the solvolytic hydrolysis of NAD+
Berti, Paul J.,Schramm, Vern L.
, p. 12069 - 12078 (2007/10/03)
The transition state structure has been determined for the pH- independent solvolytic hydrolysis of NAD+. The structure is based on kinetic isotope effects (KIEs) measured for NAD+'s labeled in various positions of the ribose ring and in the leaving group nitrogen. The KIEs for reactions performed at 100°C in 50 mM NaOAc (pH 4.0) were as follows: 1-15N, 1.020 ± 0.007; 1'-14C, 1.016 ± 0.002; [1-15N,1'-14C], 1.034 ± 0.002; 1'- 3H, 1.194 ± 0.005; 2'-3H, 1.114 ± 0.004; 4'-3H, 0.0997 ± 0.001; 5'3H, 1.000 ± 0.003; 4'-18O, 0.988 ± 0.007. The transition state structure was determined using bond energy/bond order vibrational analysis to predict KIEs for trial transition state models. The structure that most closely matches the experimental KIEs defines the transition state. A structure interpolation method was developed to generate trial transition state structures and thereby systematically search reaction coordinate space. Structures are generated by interpolation between reference structures, reactant NAD+ and a hypothetical {ribo-oxocarbenium ion plus nicotinamide} structure. The point in reaction coordinate space where all the predicted KIEs matched the measured ones was considered to locate the transition state structure. This occurred when the residual bond order to the leaving group nicotinamide, n(LG,TS), was 0.02 (bond length = 2.65 A?) and the bond order to the approaching nucleophile, n(Nu,TS), was 0.005 (3.00 A?). Thus, bond-breaking and bond-making in this A(N)D(N) reaction are asynchronous, and the transition state has a highly oxocarbenium ion-like character.
Cyclic ADP-ribose via stereoselective cyclization of β-NAD
Yamada, Shinji,Gu, Qu-Ming,Sih, Charles J.
, p. 10787 - 10788 (2007/10/02)
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