Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.2.42 (DTA)
 1,693 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have suggested that tyrosine-65 (Tyr-65) of diphtheria toxin (DT) is located at the active site. To investigate the role of Tyr-65 in NAD binding and the ADP-ribosylation of elongation factor-2 (EF-2), we changed this residue to alanine and phenylalanine by site-directed mutagenesis of a synthetic gene encoding the catalytic fragment of DT (DTA). The alanine mutant was greatly diminished in ADP-ribosylation activity (350-fold) and NAD-glycohydrolase activity (88-fold), whereas the phenylalanine mutant was reduced in these activities only slightly. Dissociation constants (Kd) for NAD binding were 15 microM for wild-type DTA, 26 microM for the phenylalanine mutant, and greater than 800 microM NAD for the alanine mutant. However, both mutant enzymes were found to bind adenosine with nearly equal affinity as wild-type DTA. These results support a model of ADP-ribosylation in which the phenolic ring of Tyr-65 interacts with the nicotinamide ring of NAD, orienting the N-glycosidic bond of NAD for attack by the incoming nucleophile in a direct displacement mechanism.
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PMID:Active-site mutations of diphtheria toxin: role of tyrosine-65 in NAD binding and ADP-ribosylation. 780 11

The ternary chelates of piroxicam (Pir) and tenoxicam (Ten) with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in the presence of various amino acids such as glycine (Gly) or dl-phenylalanine (PhA) were prepared and characterized with different physicochemical methods. IR spectra confirm that Pir and Ten behave as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its deprotonated carboxylic group. In addition, PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its deprotonated carboxylic and amino groups. The solid reflectance spectra and magnetic moment measurements confirm that all the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. Thermal behaviour of the complexes is extensively studied using TG and DTA techniques. TG results show that water molecules (hydrated and coordinated) and anions are removed in the first and second steps while Gly, PhA, Pir and Ten are decomposed in the next and subsequent steps. The pyrolyses of the chelates into different gases are observed in the DTA curves as exo- or endothermic peaks. Also, phase transition states are observed in some chelates. Different thermodynamic parameters are calculated using Coats-Redfern method and the results are interpreted.
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PMID:Synthesis and thermal characterization of new ternary chelates of piroxicam and tenoxicam with glycine and DL-phenylalanine and some transition metals. 1661 14

Single crystals of L-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time.
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PMID:Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique. 2341 4

A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.
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PMID:Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol. 2345 42

A new six intraperitoneal injections insulin-mimetic vanadyl(IV) compounds [(VO)(FA)(AAn)] (where n = 1-6: AA1 = isoleucine, AA2 = threonine, AA3 = proline, AA4 = phenylalanine, AA5 = lysine, and AA6 = glutamine) were synthesized by the chemical reactions between folic acid (FA), VOSO4, and amino acids (AAn) with equal molar ratio 1:1:1 in neutralized media. These complexes were characterized by elemental analysis and estimation of vanadyl(IV) metal ions. The thermal stability behavior of these complexes was studied by TG-DTG-DTA analyses. The structures of these complexes were elucidated by spectroscopic methods like infrared, electron spin resonance (ESR), and solid reflectance spectroscopes. The powder X-ray diffraction (XRD) study suggested the crystalline nature of the complexes. Magnetic moments and electronic spectra revealed the square-pyramid geometrical structure of the complexes. The conductivity results refereed that all synthesized vanadyl(IV) complexes were of a non-electrolyte behavior. The infrared spectra assignments of these complexes revealed that the FAH2 and AAn chelates act as a bidentate ligation. The chelation towards vanadyl (IV) ions existed via deprotonation of one of the carboxylic groups of FAH2 drug ligand, and so amino acids act as bidentate ligands via N-amino and O-carboxylate groups. Both scanning and transmission electron microscope (SEM and TEM) techniques were used to investigate the surface morphology. The main task of this research is the aim of designing a new insulin alternative antidiabetic drug agent. The antidiabetic efficiency of these complexes was evaluated in streptozotocin-induced diabetic male albino rats. Liver and kidney functions, insulin and blood glucose levels, lipid profile, and superoxide dismutase antioxidant (SOD) are verified identifiers for the efficiency of VO(IV)/FA/AAn system compounds as antidiabetic drug agents.
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PMID:Synthesis, Characterization, and Anti-diabetic Activity of Some Novel Vanadium-Folate-Amino Acid Materials. 3244 14