Cyanide-resistant respiration in Euglena gracilis does not correlate with mitochondrial cytochrome O content

Conference · Fri Mar 15 00:00:00 EST 1991 · FASEB Journal (Federation of American Societies for Experimental Biology); (United States)

OSTI ID:5173456

Devars, S; Uribe, A; Torres-Marquez, M E; Gonzalez-Halphen, D ^[1]; Moreno-Sanchez, P ^[2]

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1. Inst. Nacional de Cardiologia, (Mexico)
2. U.N.A.M. (Mexico)

Basal respiration Euglena gracilis cells grown in the dark with distinct carbon sources showed different sensitivity to KCN: 1-10% inhibition by 0.1 mM KCM for cells grown with glutamate+malate (g+m) and 40-55% for those grown with peptone+acetate (p+a). The basal respiration was stimulated 1.6 to 2.4 times by TMPD: the values reached by cells grown in g+m resembled those of p+a cells, suggesting a similar maximal cytochrome oxidase activity in both types. Dixon plots for KCM showed two components in basal and TMPD-stimulated respiration with K{sub i} values of 4-10 and 70-80 {mu}M for TMPC-stimulated respiration and 20-50 and 400-600 {mu}M for basal activity. Thus, the distinct sensitivities to KCN seems not to be due to a different content of aa{sub 3} in the cells, not to different K{sub i} for the inhibitor. Diphenyl amine, an inhibitor of alternate respiratory pathways, inhibited 85-95% basal respiration with a single K{sub i} value of 0.15-0.2 mM and 40-60% TMPD-stimulated activity. Determination of cytochrome o content, the postulated alternate oxidase, showed no differences in the cells grown with distinct carbon sources. Then the different sensitivity to cyanide is more likely related to the oxidation of different substrates.

• OSTI ID: 5173456
• Report Number(s): CONF-9104107-; CODEN: FAJOE
• Journal Information: FASEB Journal (Federation of American Societies for Experimental Biology); (United States), Vol. 5:5; Conference: 75. annual meeting of the Federation of American Societies for Experimental Biology (FASEB), Atlanta, GA (United States), 21-25 Apr 1991; ISSN 0892-6638
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CYANIDES
TOXICITY
EUGLENA
SENSITIVITY
CYTOCHROME OXIDASE
ENZYME ACTIVITY
RESPIRATION
SUBSTRATES
ALGAE
ANIMALS
ENZYMES
EUGLENOPHYCOTA
HAEM DEHYDROGENASES
INVERTEBRATES
MASTIGOPHORA
MICROORGANISMS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PLANTS
PROTEINS
PROTOZOA
UNICELLULAR ALGAE
560300* - Chemicals Metabolism & Toxicology