Spectroscopy atomic absorption, binding

The presence of calcium in horseradish peroxidase was demonstrated originally by Haschke and Friedhoff, working with the C and A (imspec-ified, but likely to have been predominantly A2) isoenzymes (209). HRP C and HRP A contain 2.0 0.13 and 1.4 0.19 moles calcium per mole enzyme, respectively, as determined by atomic absorption spectroscopy. Incubation in 6 M guanidinium hydrochloride and 10 mM EDTA for 4 hours at neutral pH and room temperature gave calcium-depleted enzymes with specific activities decreased by 40% and 15%, respectively. The thermal stability of calcium-depleted HRP C was also reduced compared to native enzyme. Reconstitution was successful only with calcium-depleted HRP C (209). It remains to be established whether this reflects true structural differences between the calcium binding sites of the two isoenz5unes, or is a consequence of the relatively harsh... 

Zinc-binding components of urine were examined using modified gel chromatography (15). Urine (3 ml) was chromatographed on Sephadex G-25 columns (2.5 x 40 cm) equilibrated with a buffer containing 10 ppm Zn as Zn(N03)2 and 10 mM Tris buffer, pH 7.4. Fractions of 3 ml were analyzed by atomic absorption spectroscopy. Void volume of the column was determined with blue dextran. 

Abbreviations AAS, atomic absorption spectroscopy AES, Auger electron spectroscopy AFM, atomic force microscopy BE, binding energy DFG, difference frequency generation DFT, density functional theory EBL, electron beam lithography EELS, electron energy loss spectroscopy ETEM, environmental transmission electron microscopy fee, face-centered cubic FEM/FIM, fleld emission... 

Aminoalkylsilane atomic absorption spectroscopy Amino acid transporter alpha-1-antitrypsin Adenoassociated vims Abscisic acid, a plant hormone ATP-binding cassette antigen-binding cell... 

Modem methods for study of metal-activated enzymes include NMR and ESR spectroscopy, water relaxation rates by pulsed NMR (PRR), atomic absorption, Mbssbauer, X-ray and neutron diffraction, high-resolution electron microscopy, UV/visible/IR spectroscopy, laser lanthanide pertubation methods, fluorescence, and equilibrium and kinetic binding techniques. Studies with Mg(II)-activated enzymes have been hampered by the lack of paramagnetic or optical properties that can be used to probe its environment, and the relative lack of sensitivity of other available methods initial velocity kinetics, changes in ORD/CD, fluorescence, or UV properties of the protein, atomic absorption assays for equilibrium binding, or competition with bound Mn(II) °. Recent developments in Mg and 0-NMR methodology have shown some promise to provide new insights . ... 

Differences between the interaction of DNA with alkaline-earth and transition divalent metal ions result from investigations made on the binding constants (K ) using polarography, atomic absorption spectroscopy, and sedimentation analysis. For the alkaline-earth metals, K is decreased, and this is confirmed by the lower coordination tendency compared to that of the nucleo-bases. 

High, K. A., Blais,J. S., Methven, B. A.J., and McLaren,J.W. (1995). Probing the characteristics of metal-binding proteins using high-performance liquid chromatography-atomic absorption spectroscopy and inductively coupled plasma mass spectrometry. Ajiafysr (London) 120(3), 629. 

XPS X-ray photoelectron spectroscopy Absorption of a photon by an atom, followed by the ejection of a core or valence electron with a characteristic binding energy. Composition, oxidation state, dispersion... 

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