56499-56-0Relevant academic research and scientific papers
Histidine triad nucleotide-binding proteins HINT1 and HINT2 share similar substrate specificities and little affinity for the signaling dinucleotide Ap4A
Strom, Alexander,Tong, Cher Ling,Wagner, Carston R.
, p. 1497 - 1505 (2020/02/25)
Human histidine triad nucleotide-binding protein 2 (hHINT2) is an important player in human mitochondrial bioenergetics, but little is known about its catalytic capabilities or its nucleotide phosphoramidate prodrug (proTide)-activating activity akin to the cytosolic isozyme hHINT1. Here, a similar substrate specificity profile (kcat/Km) for model phosphoramidate substrates was found for hHINT2 but with higher kcat and Km values when compared with hHINT1. A broader pH range for maximum catalytic activity was determined for hHINT2 (pK1?=?6.76?±?0.16, pK2?=?8.41?±?0.07). In addition, the known hHINT1-microphthalmia-inducing transcription factor-regulating molecule Ap4A was found to have no detectable binding to HINT1 nor HINT2 by isothermal titration calorimetry. These results demonstrate that despite differences in their sequence and localization, HINT1 and HINT2 have similar nucleotide substrate specificities, which should be considered in future proTide design and in studies of their natural function.
Magnesium Ion Catalyzed P-N Bond Hydrolysis in Imidazolide-Activated Nucleotides. Relevance to Template-Directed Synthesis of Polynucleotides
Kanavarioti, Anastassia,Bernasconi, Claude F.,Doodokyan, Donald L.,Alberas, Diann J.
, p. 7247 - 7257 (2007/10/02)
Magnesium, an ion necessary in enzymatic as well as in nonenzymatic template-directed polynucleotide-synthesizing reaction, has been found to catalyze the hydroxide ion attack on the P-N bond of selected 5'-monophosphate imidazolide derivatives of nucleotides, such as guanosine 5'-monophosphate 2-methylimidazolide (2-MeImpG), guanosine 5'-monophosphate imidazolide (ImpG), and adenosine 5'-monophosphate 2-methylimidazolide (2-MeImpA).Calcium ion behaves similarly, but quantitatively the effects are smaller.Pseudo-first-order rate constants of 2-MeImpG and ImpG hydrolysis as a function of Mg(2+) concentration have been obtained in the range 6 +/-, imidazolide moiety protonated) with OH(1-) rather than reaction of the anionic form (S(1-), imidazolide moiety deprotonated) with water.This conclusion is based on a study of the N-methylated substrates N-MeImpG and 1,2-diMeImpG, respectively, which were generated in situ by the equilibrium reaction of ImpG with N-methylimidazole and 2-MeImpG with 1,2-dimethylimidazole, respectively.In contrast, in the absence of Mg(2+) the reaction of S(1-) with water competes with the reaction of SH+/- with OH(1-).The present study bears on the mechanism of the Mg(2+)-catalyzed template-directed synthesis of oligo- and polynucleotides derived from 2-MeImpG and on thecompetition between oligonucleotide synthesis and hydrolysis of 2-MeImpG.
