Time-resolved EPR spectroscopy. Stopped-flow EPR apparatus for biological application

Sequential mechanism of refolding of carbonic anhydrase B

“…ESR spectra and the kinetics of their changes were measured with a Varian E3 ESR spectrometer (USA) and an SFA-1 stopped-flow attachment (GDR) [9]. Fluorescence, absorption and CD spectra were measured with an Aminco SPF-1000 cs spectrofluorimeter (USA), an M-40 spectrophotometer (GDR) and a Jobin Iron mark IIIS spectropolarimeter (France).…”

An advanced EPR stopped-flow apparatus based on a dielectric ring resonator

“…Examples are the decay of stable nitroxide radicals during reduction by ascorbate [1][2][3] or dithionite [4], and formation and decay of semi-dehydro ascorbate radicals during the oxidation of ascorbate by Ce 4+ [5,1]. Radicals that are not EPR-detectable in the liquid state due to short relaxation times T 1 (linewidth broadening), as e.g., hydroxyl (OH Å ), superoxide ðO ÅÀ 2 Þ, or alkyl thiyl (R-S Å ), cannot be studied directly by EPR-SF techniques.…”

“…The SF instrument described by Klimes et al [5] employed a conventional rectangular waveguide H 102 resonator with a large sample volume and a rather large dead volume (the volume between mixer and EPR-active region). This is unfavorable for a high time resolution, but was partly compensated in this set-up by a high flow-rate, a pressure-resistive EPR cell, and a hard-stop valve leading to a time resolution of about 1 ms.…”

“…[1]. b Data refer to an improved instrument in comparison to those in [5] which was produced in 1983-1990 in the Institute of Scientific Instruments, Berlin-Adlershof, which was applied in [8][9][10][13][14][15]. c A shorter dead time of 0.065 ms was given for this apparatus in [12].…”

Stopped-Flow FT-IR Spectroscopy of Aqueous Solutions Using Attenuated Total Reflectance

“…The original stopped-ow technique 5 provides a m ethod for rapidly mixing two or m ore solutions and then monitoring the progress of the reaction via ultraviolet or visible spectroscopy. Additional methods of m onitoring, such as MS, [6][7][8][9] NMR, 10 -14 EPR, [15][16][17] and Raman spectroscopy, 18,19 are possible, but they do not have the widespread applicability that FT-IR possesses. Stopped-ow infrared spectroscopy has been reported using dispersive instruments 20 -25 or infrared lasers, [26][27][28] but the designs generally are capable of collecting data at a single wavelength.…”