The Equilibria and Reaction Rates of Nicotinamide-Adenine Dinucleotide and Its Related Compounds with Cyanide Ion in the Presence of Polyelectrolytes
1974; Elsevier BV; Volume: 249; Issue: 11 Linguagem: Inglês
10.1016/s0021-9258(19)42609-4
ISSN1083-351X
Autores Tópico(s)Thermodynamic properties of mixtures
ResumoAbstract The rate and equilibrium constants for addition of cyanide ions to β-nicotinamide-adenine dinucleotide (βNAD+), αNAD+ and nicotinamide mononucleotide (NMN) were studied in the presence and absence of polyelectrolytes and surfactants. The polymers examined were poly(4-vinyl-N-butylpyridinium bromide) (C4PVP), poly(4-vinyl-N-benzylpyridinium chloride) (BzPVP), copolymer of 4-vinyl-N-benzylchloride and 4-vinyl-N-n-cetylbromide (C16BzPVP),copolymer of diethyldiallylammonium chloride and sulfurdioxide (DECS), DNA, poly(A), poly(I), poly(C), and poly(U). The surfactant was cetyltrimethylammonium bromide (CTABr). All of the electrolytes investigated, except anionic polyelectrolytes, increased the second order rate constant of the forward process ((→)/k) of the cyanide addition reaction in the order, αNAD+ g βNAD+ g NMN+. The order was explained by the difference in the effective local charges of the substrates. The increase was in the order, KC1 l CaCl2 l DECS l C4PVP l BzPVP l C16BzPVP, suggesting the simultaneous contribution of hydrophobic and electrostatic interactions between βNAD+ (αNAD+ or NMN) and the polyelectrolytes. On the contrary, the backward reaction was decelerated by the polyelectrolytes. The thermodynamic quantities of the cyanide addition reaction, i.e. the free energy, enthalpy, and entropy of activation, and the free energy, enthalpy, and entropy of reaction, were derived. The acceleration by polyelectrolyte was due to entropic gain, in contrast with many of the previously studied systems.
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