Epr in Chromatophores From Rhodospirillum Rubrum and in Quantasomes From Spinach Chloroplasts

Abstract

In the penultimate paragraph of the article entitled "EPR in Chromatophores from Rhodospirillum rubrum and in Quantasomes from Spinach Chloroplasts," by G. M. Androes, M. F. Singleton, and M. Calvin, which appeared in these PRO-CEEDINGS, 48, 1022-1031(1962, the results of Chance and Nishimura were incorrectly quoted. This paragraph (on page 1030) should read as follows:"The photo-induced EPR observed in the chromatophores occurs reversibly at all temperatures studied, while that observed in the quantasomes occurs irreversibly at low temperature. This difference in behavior is not paralleled by certain photoinduced changes in optical density which occur in these types of photosynthetic materials, and which are assigned to the same kind of molecule in both types of system. Chance and Nishimura"9 have found changes in optical density at -550, -520, and -420 mgt in the bacterium Chromatium which occur irreversibly at 800K, while Witt et al.20 have found changes in optical density at -555, -420, and -400 m,4 which occur irreversibly in Chlorella at -150'C. The changes in both types of material are assigned to a cytochrome. Thus, it appears that the photoinduced EPR observed in these systems is not directly associated with the photoinduced oxidation of a cytochrome." M. CALVIN 1022 BIOCHEMISTRY: ANDROES, SINGLETON, AND CALVIN PROC. N. A. S.Summary.-Production of a diffusible collagenolytic factor operating at neutral pH and physiologic temperature on undenatured collagen was demonstrated in living animal tissues in culture. Cultivation of bullfrog tadpole tissues (skin, gut, and gills) on thermally reconstituted neutral calf and guinea pig skin collagen gels resulted in degradation of the substrate to dialyzable collagen peptides. This substrate was not attacked by the common proteolytic enzymes, by Cathepsin C, by tadpole tissue extracts, or by killed tadpole tissue. It is proposed that the experimental system used here may be developed into a quantitative assay for collagenolytic activity in small tissue fragments.

Electron spin resonance in biological tissues

“…These were suspended in an aqueous medium and subjected to different conditions of illumination. Since that first experiment, this field has been studied extensively by these workers and many others (Sogo, Pon and Calvin 1957;Bubnov, Krasnovskii, Umrikhina, Tsepalov and Shliapintokh 1960;Allen, Piette and Murchio 1962;Androes, Singleton and Calvin 1962;Storey, Monita and Cadena 1962;Androes, Singleton, Biggins and Calvin 1963;Commoner, Kohl and Townsend 1963;Kohl, Townsend, Commoner, Crespi, Dougherty and Katz 1965;Kharitonenkov and Kalichava 1966).…”

Electron Spin Resonance of Chlorophyll and the Origin of Signal I in Photosynthesis

“…The most prominent of the photo-esr signals (Signal I) is rapidly reversible, has the free electron gvalue 2.0025, a peak-to-peak linewidth (AH) of about 7.5 g (plants) or about 9.5 g (bacteria), a Gaussian line shape, and no hyperfine structure. Subsequent esr studies (critically reviewed by Weaver (2)) on chloroplast or chromatophore preparations (3)(4)(5)(6), active-center preparations (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), organisms of unusual isotopic composition (20,21), and on in vitro chlorophyll systems (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31) have made it probable that Signal I arises by the photooxidation of special chlorophyll molecules located in the photosynthetic reaction center, and that this is the chlorophyll responsible for the long-wavelength absorption associated with the reaction center (32) (P700, plants; or P870, bacteria). It has further been suggested (21) that Signal I is due to the formation of Chl+-or BChl+-; however, Signal I is much narrower than the esr signals recorded from Chl+.. To explain the unusual esr and spectral properties of reaction-center chlorophyll, chlorophyll aggregation of an unspecified nature (33), chlorophyll-lipid and chlorophyll-protein interactions (34), or perturbations in the chlorophyll -r system caused by unspecified changes in the environment (24) have been suggested.…”

Multiplicity of Electron Transport Reactions in Bacterial Photosynthesis

“…Low-temperature studies with R . rubrum cells and chromatophores have revealed that the ESRL signal has two components exhibiting different decay characteristics at the temperature of liquid nitrogen (Sogo et al 1959; Androes et al 1962); comparable effects can be produced at physiological temperatures by dehydrating chromatophores (Cost, Bolton & Frenkel, 1969). Under these conditions, the fast decay component of the chromatophore ESRL signal forms and decays reversibly, while the signal corresponding to the slow component is formed but does not decay.…”