TY - JOUR
T1 - Determination of dissolved oxygen in photosynthetic systems by nitroxide spin-probe broadening
AU - Belkin, Shimshon
AU - Mehlhorn, Rolf J.
AU - Packer, Lester
PY - 1987/2/1
Y1 - 1987/2/1
N2 - Concentrations of dissolved oxygen were monitored by following the width of the midfield line of the electron spin resonance spectrum of a nitroxide spin-probe. Measurements of peak-to-trough widths of first derivative spectra yielded accurate data over a high range of O2 concentrations (up to 5 mm). Continuous traces of second harmonic line heights yielded similar results and proved to be advantageous for kinetic measurements, but were nonlinear and less sensitive at O2 levels above 2 mm. Photosynthetic oxygen evolution and respiratory oxygen uptake in the cyanobacterium Agmenellum quadruplicatum were thus examined over a broad range of oxygen concentrations. Upon prolonged (>1 min) illumination, effects of photooxidative damage to both photosynthesis and respiration were demonstrated in the same experimental system. With the addition of an impermeable paramagnetic broadening agent, rapid transients in intracellular concentrations of dissolved O2 also could be measured.
AB - Concentrations of dissolved oxygen were monitored by following the width of the midfield line of the electron spin resonance spectrum of a nitroxide spin-probe. Measurements of peak-to-trough widths of first derivative spectra yielded accurate data over a high range of O2 concentrations (up to 5 mm). Continuous traces of second harmonic line heights yielded similar results and proved to be advantageous for kinetic measurements, but were nonlinear and less sensitive at O2 levels above 2 mm. Photosynthetic oxygen evolution and respiratory oxygen uptake in the cyanobacterium Agmenellum quadruplicatum were thus examined over a broad range of oxygen concentrations. Upon prolonged (>1 min) illumination, effects of photooxidative damage to both photosynthesis and respiration were demonstrated in the same experimental system. With the addition of an impermeable paramagnetic broadening agent, rapid transients in intracellular concentrations of dissolved O2 also could be measured.
UR - http://www.scopus.com/inward/record.url?scp=0023294608&partnerID=8YFLogxK
U2 - 10.1016/0003-9861(87)90055-5
DO - 10.1016/0003-9861(87)90055-5
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C2 - 3028269
AN - SCOPUS:0023294608
SN - 0003-9861
VL - 252
SP - 487
EP - 495
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 2
ER -