Specific selenium-containing macromolecules in the marine diatom Thalassiosira pseudonana

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.86.1.192· OSTI ID:6905646

Price, N M; Harrison, P J

Thalassiosira pseudonana Husedt (Hasle and Heimdal) clone 3H was grown in axenic culture in artificial sea water medium containing 10/sup -8/ molar Na/sub 2//sup 75/SeO/sub 3/. Biochemical distribution of radiolabeled Se was determined by solvent extraction techniques, gel filtration, and polyacrylamide gel electrophoresis. Of the total cellular Se, 51% was protein bound. Two soluble macromolecules of 21 and 29 kilodaltons contained /sup 75/Se. These results are the first to provide evidence of specific Se-containing compounds in a photosynthetic organism. Glutathione peroxidase (GSH-Px) activity was measured in cell-free extracts and on nondenaturing poly-acrylamide gels by a glutathione-reductase coupled assay. Two enzymes showing GSH-Px activity were present. One enzyme was active with H/sub 2/O/sub 2/ and tert-butyl hydroperoxide (tBOOH); consistent with know Se-dependent GSH-Pxs, but the other enzyme was only active with tBOOH. Co-migration of the H/sub 2/O/sub 2/-active GSH-Px and /sup 75/Se on nondenaturing polyacrylamide gels provides evidence that T. pseudonana contains a Se-dependent GSH-Px. The molecular weight of one of the /sup 75/Se-labeled marcromolecules is identical with the weight of previously characterized GSH-Px subunits. We conclude that the obligate requirement for Se in Thalassiosira pseudonana is due in part to the presence of the selenoenzyme glutathione peroxidase.

• Research Organization: Univ. of British Columbia, Vancouver (Canada)
• OSTI ID: 6905646
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 86:1; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALGAE
BETA DECAY RADIOISOTOPES
CELL CULTURES
CLONE CELLS
DAYS LIVING RADIOISOTOPES
DIATOMS
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENZYME ACTIVITY
ENZYMES
EVEN-ODD NUCLEI
GLUTATHIONE
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MOLECULAR WEIGHT
NUCLEI
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PEPTIDES
PEROXIDASES
PLANTS
POLYPEPTIDES
PROTEINS
RADIOISOTOPES
RADIOPROTECTIVE SUBSTANCES
SELENIUM
SELENIUM 75
SELENIUM ISOTOPES
SEMIMETALS
TRACER TECHNIQUES
UPTAKE