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Growth Cycle‐Dependent Overproduction and Accumulation of Protoporphyrin IX in Tetrahymena : Effect of Heavy Metals 1
Author(s) -
RUBEN LARRY,
LAGESON JEAN,
HYZY BOB,
HOOPER ALAN B.
Publication year - 1982
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.1550-7408.1982.tb04018.x
Subject(s) - protoporphyrin ix , overproduction , protoporphyrin , tetrahymena pyriformis , heme , porphyrin , tetrahymena , chemistry , biochemistry , ciliate , hematoporphyrin , cell cycle , microbiology and biotechnology , biology , cell , enzyme , genetics , photodynamic therapy , organic chemistry
ABSTRACT Cells of the ciliate Tetrahymena pyriformis GL overproduce and accumulate massive quantities of the heme intermediate, protoporphyrin IX. Protoporphyrin is localized intracellularly in discrete membranous compartments. The amount of porphyrin stored in the cell changes dramatically as cells progress through the growth cycle. Porphyrin overproduction is stimulated by δ‐aminolevulinic acid, but only during the mid‐stationary phase. Overproduction of protoporphyrin IX apparently results from an increase, late in the growth cycle, of activities subsequent to δ‐aminolevulinic acid synthetase. Feedback inhibition in the pathway by accumulated protoporphyrin IX does not occur. The presence of Co 2+ completely inhibits accumulation of protoporphyrin IX in a manner reversed by δ‐aminolevulinic acid. Sn 4+ stimulates protoporphyrin IX accumulation in the culture.