Disease relevance of hydrogen anion

• Accumulation of 10B in the central degenerative areas of human glioma and colon carcinoma spheroids after sulfhydryl boron hydride administration [1].
• In a transplantable Harding-Passey melanoma in mice, it was found that the sulfhydryl boron hydride Na2B12H11SH presently used for therapy of glioblastoma clears blood, muscle, and brain very rapidly [2].
• 6. A comparison of the ternary complexes in R67 and E. coli DHFRs suggests that enzymic raising of the pK(a) at N5 can significantly increase the catalytic efficiency of the hydride transfer step [3].
• The mechanism for fumarate reduction by the soluble fumarate reductase from Shewanella frigidimarina involves hydride transfer from FAD and proton transfer from the active-site acid, Arg-402 [4].
• Rates of hydride transfer at pH 7.65 cover a wide range, from 7 s-1 for DHFR from a strain of Lactobacillus casei (LCDHFR1) to 3000 s-1 for recombinant human DHFR (rHDHFR) [5].

Psychiatry related information on hydrogen anion

• For examination of the possibility of an NAD+-mediated intramolecular hydride transfer of the 4'-hydrogen to a position on the side chain of oxoimidazolepropionate, the origins of hydrogen at positions 2 and 3 in the propionate chain were studied as a function of reaction time and extent of exchange of the 4'-hydrogen [6].
• Hydride reduction of the amide carbonyl in 1 also yielded compounds having a slightly lower ED50 against convulsions induced by electroshock and a much lower TD50 in the rotorod assay [7].
• Neuropsychological tests and self-report personality inventories were administered to 14 workers and rescue squad personnel approximately 2 months following mild exposure to pentaborane, a highly toxic volatile liquid boron hydride [8].

High impact information on hydrogen anion

• Such tunnelling also allows sequential electron transfer in catalytic sites to surmount radical transition states without involving the movement of hydride ions, as is generally assumed [9].
• The proton-coupled electron transfer reaction catalyzed by soybean lipoxygenase and the hydride transfer reaction catalyzed by dihydrofolate reductase are discussed [10].
• Low-valent ruthenium and iridium hydride complexes are highly useful redox Lewis acid and base catalysts [11].
• Impact of distal mutations on the network of coupled motions correlated to hydride transfer in dihydrofolate reductase [12].
• This active site geometry allows for catalysis of hydride equivalent transfer to the >C5=NH of PQQ(NH) by concerted Glu-171CO(2)(-) general-base removal of the H-OCH3 proton and Arg-324H+ general-acid proton transfer to the imine nitrogen [13].

Chemical compound and disease context of hydrogen anion

• Simulations of hydride and deuteride transfer catalyzed by dihydrofolate reductase from the hyperthermophile Thermotoga maritima (TmDHFR) are presented [14].
• A remarkable correlation has been discovered between fluorescence lifetimes of bound NADPH and rates of hydride transfer among mutants of dihydrofolate reductase (DHFR) from Escherichia coli [15].
• The alteration is stereospecific, in agreement with measured changes in vibrational spectra, and leads to an understanding of the correlation, established some time ago by crystallography and NMR, between the nicotinamide glycosidic bond torsion angle (anti/syn) and the stereospecificity of hydride transfer [16].
• In this step, the hydride transfer and the scission of an overall conserved active site cysteine residue (Cys146 in Escherichia coli) take place in a concerted but very asynchronous way [17].
• Mechanism of hydride transfer during the reduction of 3-acetylpyridine adenine dinucleotide by NADH catalyzed by the pyridine nucleotide transhydrogenase of Escherichia coli [18].

Biological context of hydrogen anion

• The transient-state kinetics of hydride transfer catalyzed by mixtures of recombinant domains I and III were studied by stopped-flow spectrophotometry [19].
• Our data suggest that the decarboxylase domain catalyzes both hydride abstraction (oxidation) from the C-4' position and the subsequent decarboxylation [20].
• Thus, it can be concluded that it is only the structure of the substrates that prevails in forming a ternary complex enzyme-NAD-thiohemiacetal productive (or not) for hydride transfer in the acylation step [21].
• In dI, the lifetime of Trp-72 phosphorescence was barely affected by protein dimerization, cofactor binding, complexation with the NADP(H)-binding component (dIII), or by the introduction of two amino acid substitutions at the hydride-transfer site [22].
• It is suggested that the rigidity and structural invariance of the protein domain (dI.1) housing this Trp residue are important to the mechanism of transhydrogenase: movement of dI.1 affects the width of a cleft which, in turn, regulates the positioning of bound nucleotides ready for hydride transfer [22].

Anatomical context of hydrogen anion

• However, very little isotope was recovered from the washed mitochondria, indicating the possibility of hydride ion translocation in the absence of nucleotide translocation [23].
• We assessed baseline selenium levels in serum and in toenail specimens (reflecting long-term intake) and post-intervention selenium levels in serum, and in prostate and SV tissues using hydride generation atomic fluorescence spectroscopy [24].
• Chinese hamster ovary and mouse hybridoma cells were treated with silica hydride after being photosensitized with singlet oxygen, hydroxyl/superoxide, and hydroxyl reactive oxygen species through the use of rose Bengal diacetate, malachite green, and N,N'-bis(2-hydroperoxy-2-methoxyethyl)-1,4,5,8-naphthaldiimide, respectively [25].
• This simple, rapid, sensitive, reliable, and economical assay for bismuth in plasma, erythrocytes, and urine is based on atomic absorption spectrophotometry with hydride generation [26].
• It is located in the inner mitochondrial membrane and catalyzes hydride ion transfer between NAD(H) and NADP(H) in a reaction that is coupled to proton translocation across the inner membrane [27].

Associations of hydrogen anion with other chemical compounds

• In the absence of this binding site in QR2, the enzyme retains the essential catalytic machinery, including affinity for FAD, but cannot bind phosphorylated hydride donors [28].
• The effect of the mutation is both to increase the dissociation rate of dihydrofolate and decrease the rate of hydride transfer thus changing the rate-limiting step in catalysis from product loss (leucine-54) to hydride transfer (glycine-54) [29].
• The protonmotive force alters the affinity of the transhydrogenase for substrates, accelerates the rate of hydride ion transfer from NADH to NADP, and shifts the equilibrium of this reaction toward NADPH formation [30].
• This enzyme couples hydride transfer between NAD(H) and NADP(H) to proton translocation across a membrane and is only active as a dimer [22].
• The nicotinamide nucleotide transhydrogenases of mitochondria and bacteria are proton pumps that couple direct hydride ion transfer between NAD(H) and NADP(H) bound, respectively, to extramembranous domains I and III to proton translocation by the membrane-intercalated domain II [31].

Gene context of hydrogen anion

• The truncated AR delta 303-315 displayed a NADPH/D isotope effect in kcat and an increased D(kcat/Km) value for DL-glyceraldehyde, suggesting that hydride transfer has become partially rate-limiting for the overall reaction [32].
• These values suggest that a significant 15N kinetic isotope effect is not associated with hydride transfer for LADH and FDH [33].
• The lack of a Mg(2+) ion effect on hydride transfer was further demonstrated with an E399Q mutant of ALDH1 whose rate-limiting step had been changed from NADH dissociation to hydride transfer [34].
• Detailed studies of W676H CPR indicate that further reduction of the enzyme beyond the two electron level is prevented due to the slow release of NADP(+) from the active site following the first hydride transfer from NADPH, owing to the stability of a reduced enzyme-NADP(+) charge-transfer complex [35].
• Mouse ADH2 follows an ordered bi-bi mechanism, and hydride transfer is rate-limiting for oxidation of benzyl alcohols catalyzed by the mutated and wild-type enzymes [36].

Analytical, diagnostic and therapeutic context of hydrogen anion

• Sulfhydryl boron hydride (BSH) (10B enriched) is presently used for boron neutron capture therapy of malignant gliomas [1].
• A neutron diffraction study on a single crystal of diethylsilylene complex 4b unequivocally determined the hydride ligand to be in a bridging position across the molybdenum-silicon bond (Mo-H 1.85(1) A, Si-H 1.68(1) A) [37].
• Improved assay for bismuth in biological samples by atomic absorption spectrophotometry with hydride generation [26].
• Short-column liquid chromatography with hydride generation atomic fluorescence detection for the speciation of arsenic [38].
• In this quartz interface, the methanolic HPLC eluent was nebulized by thermospray effect and pyrolyzed in a methanol/oxygen kinetic flame and the analytes were thermochemically derivatized to the hydride derivative in the presence of excess hydrogen [39].

References