DOI: 10.1126/science.165.3896.906. Paramagnetic Unit in Spinach Subchloroplast Particles: Estimation of Size

Paramagnetic Unit in Spinach Subchloroplast Particles: Estimation of Size

10.1126/science.165.3896.906

Crossref journal-article

American Association for the Advancement of Science (AAAS)

Science (221)

Abstract

A pulsed ruby laser (wavelength, 694.3 nanometers) was used to measure the dependence on light intensity of light-induced electron paramagnetic resonance (ERR) signal 1 for short flashes of uniform duration (400 microseconds). Approximately 10 18 photons per square centimeter per flash from the unattenuated beam were available to the sample of subchloroplast "system 1" particles from spinach. The experimental dependence of the EPR signal height plotted as a function of the total number of incident photons per flash was exponential. From measurement of the slope at a very low relative photon flux and the saturated EPR signal amplitude, the value for the cross section or "effective size" of the light-induced paramagnetic unit, σ EPR , was found to be 300 × 10 -17 square centimeter. This result is compared with a measured optical absorption cross section, σ 694nm , of 2.5 × 10 -17 square centimeter, for the identical sample at the laser wavelength. The hundredfold difference in size supports the thesis that the paramagnetic state is a property of an aggregate of chlorophyll molecules of the same general size as the photosynthetic unit.

Bibliography

Weaver, E. C., & Weaver, H. E. (1969). Paramagnetic Unit in Spinach Subchloroplast Particles: Estimation of Size. Science, 165(3896), 906â907.

Authors 2

E. C. Weaver (first)
H. E. Weaver (additional)

References 5 Referenced 27

ARNON, D.I., COPPER ENZYMES IN ISOLATED CHLOROPLASTS - POLYPHENOLOXIDASE IN BETA-VULGARIS, PLANT PHYSIOLOGY 24: 1 (1949). (10.1104/pp.24.1.1) / PLANT PHYSIOLOGY (1949)
EMERSON, R, The photochemical reaction in photosynthesis, JOURNAL OF GENERAL PHYSIOLOGY 16: 191 (1932). (10.1085/jgp.16.2.191) / JOURNAL OF GENERAL PHYSIOLOGY (1932)
MARGOZZI, A, A DUAL-BEAM SOURCE OF ACTINIC LIGHT FOR PHOTOSYNTHESIS RESEARCH, PHOTOCHEMISTRY AND PHOTOBIOLOGY 9: 549 (1969). (10.1111/j.1751-1097.1969.tb07324.x) / PHOTOCHEMISTRY AND PHOTOBIOLOGY (1969)
VERNON, L.P., REALTIONSHIP OF P700 ELECTRON SPIN RESONANCE SIGNAL AND PHOTOCHEMICAL ACTIVITY OF A SMALL CHLOROPLAST PARTICLE OBTAINED BY ACTION OF TRITON X-100, BIOCHEMISTRY 6: 2210 (1967). (10.1021/bi00859a044) / BIOCHEMISTRY (1967)
WEAVER, E .C., ANNUAL REVIEW OF PLANT PHYSIOLOGY 19: 283 (1968). (10.1146/annurev.pp.19.060168.001435) / ANNUAL REVIEW OF PLANT PHYSIOLOGY (1968)

Dates

Type	When
Created	18 years, 10 months ago (Oct. 5, 2006, 8:14 a.m.)
Deposited	1 year, 7 months ago (Jan. 11, 2024, 9:17 a.m.)
Indexed	1 year, 7 months ago (Jan. 11, 2024, 7:03 p.m.)
Issued	56 years ago (Aug. 29, 1969)
Published	56 years ago (Aug. 29, 1969)
Published Print	56 years ago (Aug. 29, 1969)

Funders 0

None

BibTeX

@article{Weaver_1969, title={Paramagnetic Unit in Spinach Subchloroplast Particles: Estimation of Size}, volume={165}, ISSN={1095-9203}, url={http://dx.doi.org/10.1126/science.165.3896.906}, DOI={10.1126/science.165.3896.906}, number={3896}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Weaver, E. C. and Weaver, H. E.}, year={1969}, month=aug, pages={906–907} }

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