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Thermostable Compounds Opposing Toxicity of the Carcinogen 4‐Nitroquinoline N ‐Oxide to Flagellates and Bacteria *
Author(s) -
ZAHALSKY ARTHUR C.,
KEANE MARY M.,
HUTNER S. H.,
LUBART KATHERINE J.,
KITTRELL MIRIAM,
AMSTERDAM D.
Publication year - 1963
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1963.tb01700.x
Subject(s) - euglena gracilis , carcinogen , chemistry , bacteria , tryptophan , euglena , biochemistry , hydroxylation , tetrahymena pyriformis , biology , tetrahymena , chloroplast , amino acid , genetics , gene , enzyme
SYNOPSIS. In defined media growth inhibition of the flagellates Ochromonas danica and Euglena gracilis , the photosyn thetic bacterium Rhodopseudomonas palustris , and Coryne bacterium bovis was overcome for each organism, for concentrations of 4‐nitroquinoline N ‐oxide (4‐NQO) to ca. 5 μg/ml, by a combination of L‐tryptophan, riboflavin, nicotinic acid, L‐tyrosine, and less sharply, thymine and naphtho quinones. Tryptophan used alone was effective only in rather high concentrations— ca. 0.2 mg/ml for 4‐NQO 2 μg/ml; it was competitive with 4‐NQO through this range. At least for Euglena , gramine and 5‐methyl‐DL‐tryptophan were about as effective. 4‐NQO uptake may therefore be via the trypto phan transport system. 4‐NQO may be a uniquely stable, accessible counterpart of the more polar, more carcinogenic compounds into which mammals oxidatively convert the azodye carcinogens by N‐hydroxylation and the hydrocarbon carcinogens by hydroxylation and ketonization.