| AUTHOR |
TITLE |
Fox, S., Nanthakumar, A.,
Wikstrom, M.,
Karlin, K. D.,
Blackburn, N. J. |
XAS Structural Comparisons of Reversibly Interconvertible Oxo- and Hydroxo-Bridged Heme-Copper Oxidase Model Compounds
Journal of the American Chemical Society; 1996; 118(1); 24-34. |
Experimental Section
Materials and Methods
UV-vis spectra were recorded on a Shimadzu UV 160U instrument or a Hewlett-Packard 8452A diode array spectrometer driven by a Compaq Desk Pro 386S computer using software written by On-Line Instrument Systems, Inc. (Bogart, GA). |
Digel, J. G. ,
Moore, N. D.,
McCarty, R. E. |
Influence of Divalent Cations on Nucleotide Exchange and ATPase Activity of Chloroplast Coupling Factor 1
Biochemistry; 1998; 37(31); 17209-17215. (Article) |
| Fluorescence measurements were made using an OLIS-modified SLM/Aminco SPF-500 spectrofluorometer. The excitation wavelength was 418 nm and the emission wavelength, 560 nm. Exchange was initiated by stopped-flow mixing. |
Hightower, K. E.,
McCarty, R. E. |
Influence of Nucleotides on the Cold Stability of Chloroplast Coupling Factor 1,
Biochemistry; 1996; 35(31); 10051-10057. |
Materials and Methods.
Cold dissociation was studied by ANS fluorescence using an SLM/Aminco SPF-500 spectrofluorometer modified by OLIS. The temperature in the cuvette was approximately 0 °C. CF1 was diluted to 50 µg/mL (1 mL total) in cold buffer containing 50 mM Tris-HCl (adjusted to pH 8.0 at 20 °C), 200 mM NaCl, and 30 µM ANS with or without (Mg²+ loaded samples) 5 mM EDTA to begin the assay. Free acid ANS that had been passed through a 1.5 cm x 3 cm column of Chelex 100 was used for all experiments. The ANS was excited at 360 nm, and the fluorescence emission was monitored at 430 nm. This emission wavelength was selected because it gave the maximum difference in the fluorescence of free and bound ANS. The fluorescence of bound ANS was substantially blue-shifted. |
Tanaka, M.,
Ishimori, K.,
Morishima, I. |
Luminol Activity of Horseradish Peroxidase Mutants Mimicking a Proposed Binding Site for Luminol in Arthromyces ramosus Peroxidase
Biochemistry; 1999; 38(32); 10463-10473. |
Experimental Methods
Elementary Reaction Rates in the Catalytic Cycle. Formation (k1) and reduction (k2) rates of compound I and the reduction rate (k3) of compound II under pseudo-first-order conditions were measured on a spectrophotometer (OLIS, USA) equipped with a stopped-flow mixer (Unisoku, Japan) at 25 °C in 50 mM sodium phosphate buffer, pH 7.0. More than 10-fold excess of H2O2 or substrate such as luminol and guaiacol relative to the concentration of HRP or ARP (2.0 µM) was utilized to ensure pseudo-first-order kinetics. The elementary reaction rates of k1, k2, and k3 were determined by the absorbance changes at 395, 412, and 424 nm, respectively. |
Pryor, W. A.,
Jin, X., Squadrito, G. L. |
Insensitivity of the Rate of Decomposition of Peroxynitrite to Changes in Viscosity; Evidence against Free Radical Formation
Journal of the American Chemical Society; 1996; 118(13); 3125-3128. |
Experimental Section
Kinetic Measurements.
The kinetic measurements were followed by monitoring the disappearance of peroxynitrite versus time at 302 nm on a stopped-flow spectrophotometer manufactured by Kinetic Instruments, Inc. (Ann Arbon, MI) and On-Line Instrument Service (Jefferson, GA) with a mixing time of less than 1.5 ms. |
Heyduk, A. F.,
Macintosh, A. M.,
Nocera, D. G. |
Four-Electron Photochemistry of Dirhodium Fluorophosphine Compounds
Journal of the American Chemical Society; 1999; 121(21); 5023-5032. |
Experimental Section
Other Physical Methods. Spectroscopic photolysis measurements were performed on samples contained within a cell equipped with a solvent reservoir and a 1-cm clear fused-quartz cell (Starna Cells, Inc.). The two chambers were isolated from each other by a high-vacuum Teflon valve and from the environment with a second high-vacuum Teflon valve. Bulk photolyses were performed on stirred solutions contained in a quartz reaction vessel adapted for manipulations on a high-vacuum manifold. All photolysis solutions were subject minimally to three freeze-pump-thaw cycles (10-6 Torr) prior to irradiation. Samples were irradiated at 0 °C using a 1000-W high-pressure Oriel Hg-Xe lamp. The irradiation beam passed through cutoff filters to remove high-energy light and a collimating lens prior to entering the sample chamber. Quantum yield experiments were performed by replacing the cutoff filters with 10-nm band-pass mercury line interference filters (Oriel). The progress of a photolysis reaction was monitored by absorption spectra recorded on an OLIS-modified CARY-17 spectrophotometer. |
Smith, R. D.,
Owen, W. G. |
Platelet Responses to Compound Interactions with Thrombin
Biochemistry; 1999; 38(28); 8936-8947. |
Experimental Procedures
Data were acquired for 2-5 min at 1 s intervals as digital files with the OLIS interface and software (OLIS, Inc., Bogart, GA) of the SLM fluorimeter. |
Bullesbach, E. E.,
Steinetz, B. G.,
Schwabe, C. |
Chemical Synthesis of a Zwitterhormon, Insulaxin, and of a Relaxin-like Bombyxin Derivative
Biochemistry; 1996; 35(30); 9754-9760. (Article) |
Experimental Section
Methods
Protein Determinations. Protein determinations were based on UV absorbance on an Olis Cary-15 spectrophotometer conversion (On-Line Instrument Systems, Inc.). Calculation of absorbance coefficients at 280 nm was based on tyrosine and tryptophan content of the molecules [1340 L cm-1 M-1 for tyrosine and 5600 L cm-1 M-1 for tryptophan (Long, 1968)]. |
Larrabee, J. A.,
Alessi, C. M.,
Asiedu, E. T.,
Cook, J. O.,
Hoerning, K. R.,
Klingler, L. J.,
Okin, G. S.,
Santee, S. G.,
Volkert, T. L.
|
Magnetic Circular Dichroism Spectroscopy as a Probe of Geometric and Electronic Structure of Cobalt(II)-Substituted Proteins: Ground-State Zero-Field Splitting as a Coordination Number Indicator
Journal of the American Chemical Society; 1997; 119(18); 4182-4196. |
Experimental Section
Physical Measurements. Absorption spectra were taken using a OLIS-14 UV/vis/near-IR spectrophotometer. Diffuse reflectance spectra were recorded using an OLIS-17 UV/vis/near-IR spectrophotometer equipped with a Cary-17 integrating sphere diffuse reflectance accessory. For diffuse reflectance spectra, the sample was finely ground and mixed with magnesium oxide and the spectrum was recorded using pure magnesium oxide as a reference. |
Mitchell, D. C.,
Litman, B. J. |
Effect of Protein Hydration on Receptor Conformation: Decreased Levels of Bound Water Promote Metarhodopsin II Formation
Biochemistry; 1999; 38(24); 7617-7623. |
Experimenal Methods
Kinetic Absorbance Measurements. The absorbance at 380 nm was monitored with an OLIS RSM-1000 rapid-scanning spectrophotometer operating in the single-wavelength mode. Absorbance readings were acquired every 100 μs for 100 ms. The activating flash, provided by a flashlamp, bleached 7-9% of the rhodopsin. Sheet polarizers in the flash and measuring beams polarized the flash at 54.7° relative to the polarized measuring beam. The increase in absorbance at 380 nm was well described by the sum of two exponentials. |
