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Title: Cytochrome C oxidase activity in germinating Phaseolus vulgaris l. seeds: Effects of carbon monoxide

Abstract

Cytochrome c oxidase is a key bioenergetic enzyme required for seed germination. The enzyme was isolated from 2-day germinating beans and biochemically compared to its bovine heart counterpart. Carbon monoxide, which binds to the heme a{sub 3} site of cytochrome c oxidase, we used to probe O{sub 2} utilization activity in isolated enzyme, mitochondrial particles, and whole seeds. Bean seeds under 80% CO/20% O{sub 2} exhibited 46% growth inhibition as determined by root length. Reversible, dose-dependent partial inhibition of bean seed mitochondrial respiration was observed in the presence of CO; heart mitochondria had a more sensitive, less reversible response. Effects of CO on bean and bovine heart enzyme were similar. The close correlation of CO effects observed on seedling growth, mitochondrial respiration and cytochrome oxidase activity indicate an important role for this enzyme during the early stages of seed germination.

Authors:
 [1]; ;
  1. (Colorado State Univ., Fort Collins (USA))
Publication Date:
OSTI Identifier:
6604197
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plant Physiology, Supplement; (USA); Journal Volume: 89:4
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; CARBON MONOXIDE; TOXICITY; MIXED-FUNCTION OXIDASES; ENZYME ACTIVITY; SEEDS; GERMINATION; CATTLE; DOSE-RESPONSE RELATIONSHIPS; HEART; MITOCHONDRIA; PHASEOLUS; SPROUT INHIBITION; ANIMALS; BODY; CARBON COMPOUNDS; CARBON OXIDES; CARDIOVASCULAR SYSTEM; CELL CONSTITUENTS; CHALCOGENIDES; DOMESTIC ANIMALS; ENZYMES; INHIBITION; LEGUMINOSAE; MAGNOLIOPHYTA; MAGNOLIOPSIDA; MAMMALS; ORGANOIDS; ORGANS; OXIDES; OXIDOREDUCTASES; OXYGEN COMPOUNDS; OXYGENASES; PLANTS; RUMINANTS; VERTEBRATES 560300* -- Chemicals Metabolism & Toxicology

Citation Formats

Caughey, W.S., Sowa, S., and Roos, E.E. Cytochrome C oxidase activity in germinating Phaseolus vulgaris l. seeds: Effects of carbon monoxide. United States: N. p., 1989. Web.
Caughey, W.S., Sowa, S., & Roos, E.E. Cytochrome C oxidase activity in germinating Phaseolus vulgaris l. seeds: Effects of carbon monoxide. United States.
Caughey, W.S., Sowa, S., and Roos, E.E. 1989. "Cytochrome C oxidase activity in germinating Phaseolus vulgaris l. seeds: Effects of carbon monoxide". United States. doi:.
@article{osti_6604197,
title = {Cytochrome C oxidase activity in germinating Phaseolus vulgaris l. seeds: Effects of carbon monoxide},
author = {Caughey, W.S. and Sowa, S. and Roos, E.E.},
abstractNote = {Cytochrome c oxidase is a key bioenergetic enzyme required for seed germination. The enzyme was isolated from 2-day germinating beans and biochemically compared to its bovine heart counterpart. Carbon monoxide, which binds to the heme a{sub 3} site of cytochrome c oxidase, we used to probe O{sub 2} utilization activity in isolated enzyme, mitochondrial particles, and whole seeds. Bean seeds under 80% CO/20% O{sub 2} exhibited 46% growth inhibition as determined by root length. Reversible, dose-dependent partial inhibition of bean seed mitochondrial respiration was observed in the presence of CO; heart mitochondria had a more sensitive, less reversible response. Effects of CO on bean and bovine heart enzyme were similar. The close correlation of CO effects observed on seedling growth, mitochondrial respiration and cytochrome oxidase activity indicate an important role for this enzyme during the early stages of seed germination.},
doi = {},
journal = {Plant Physiology, Supplement; (USA)},
number = ,
volume = 89:4,
place = {United States},
year = 1989,
month = 4
}
  • The effect of carbon monoxide and light on the respiration of a number of plant tissues were examined. The respiration of root or other tissue was measured at 25/sup 0/C by standard manometric techniques in a ratio of 95% CO and 5% O/sub 2/. The respiration of all eleven tissues studied was strongly inhibited by carbon monoxide. In ten of the eleven cases examined the inhibition was largely or completely eliminated by irradiation of the tissue with light. The evidence fairly well precludes the participation of a tyrosinase and definitely supports the participation of a cytochrome oxidase in respiration. 5more » references, 1 table.« less
  • The effects of metal ions on cytokinin oxidase activity extracted from callus tissues of Phaseolus vulgaris L. cv Great Northern have been examined using an assay based on the oxidation of N/sup 6/-(..delta../sup 2/-isopentenyl)-adenine-2,8-/sup 3/H (i/sup 6/ Ade) to adenine (Ade). The addition of cupric ions to reaction mixtures containing imidazole buffer markedly enhanced cytokinin oxidase activity. In the presence of optimal concentrations of copper and imidazole, cytokinin oxidase activity was stimulated more than 20-fold. The effect was enzyme dependent, specific for copper, and observed only in the presence of imidazole. The substrate specificity of the copper-imidazole enhanced reaction, asmore » judged by substrate competition tests, was the same as that observed in the absence of copper and imidazole. Similarly, in tests involving DEAE-cellulose chromatography, elution profiles of cytokinin oxidase activity determined using a copper-imidazole enhanced assay were identical to those obtained using an assay without copper and imidazole. On the basis of these results, the addition of copper and imidazole to reaction mixtures used to assay for cytokinin oxidase activity is judged to provide a reliable and specific assay of greatly enhanced sensitivity for the enzyme. The mechanism by which copper and imidazole enhance cytokinin oxidase activity is not certain, but the reaction catalyzed by the enzyme was not inhibited by anaerobic conditions when these reagents were present. This observation suggests that copper-imidazole complexes are substituting for oxygen in the reaction mechanism by which cytokinin oxidase effects cleavage of the N/sup 6/-side chain of i/sup 6/ Ade.« less
  • Development of vegetative and floral buds was found to be a key factor in establishing the way carbon is distributed among growing leaves and fruits in Phaseolus vulgaris L. plants. Leaves emerged principally during a period 14 to 32 days after planting while flowers were produced during a 10- to 12-day period near the end of leaf emergence. Timing of anthesis established the sigmoidal time course for dry weight accumulated by the composite of all fruits on the plant. During the first 12 days following anthesis, fruit growth mainly consisted of elongation and dry weight accumulation by the pod wall.more » Thereafter, seed dry weight increased for about 1 week, decreased markedly for several days, and then increased again over the next 2 weeks. Accumulation of imported carbon in individual seeds, measured by steady-state labeling, confirmed the time course for dry weight accumulation observed during seed development. Seed respiration rate initially increased rapidly along with dry weight and then remained nearly steady until seed maturation. A number of developmental events described in the literature coincided with the different phases of diauxic growth. The results demonstrated the feasibility of relating current rates of carbon import in individual seeds measured with tracer {sup 14}C to the rates of conversion of imported sucrose and use of the products for specific developmental processes. The resulting data are useful for evaluating the roles of conversion and utilization of imported sucrose in regulating import by developing seeds.« less
  • Data are reported on results of initial efforts to probe the mechanism of cytochrome oxidase function by utilizing time-resolved resonance Raman spectroscopy. Preparation of the reduced beef-heart cytochrome oxidase sample and cytochrome oxidase-CO sample is described. At the laser powers and concentrations employed, the reduced cytochrome oxidase-CO sample underwent almost complete photolysis during the laser pulse. Principal conclusions drawn from spectral analysis are that time-resolved resonance Raman investigation of the transient heme species generated by ligand photolysis is a viable technique for the study of heme-ligand dynamics in proteins other than hemoglobin. A transient proximal geometry leading to a strengthenedmore » iron-histidine bond is present in these. The interplay of porphyrin core size, pi electron density, and Fe-His bonding as modulated by heme-protein dynamics is different for the ligand binding sites of hemoglobin and cytochrome oxidase. 17 references, 1 figure.« less