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Induction of Isocitrate Lyase in Synchronous Cultures of Chlorella fusca
Author(s) -
AASBERG KARL ERIK,
LIEN TORLEIV,
KNUTSEN GJERT
Publication year - 1974
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1974.tb03699.x
Subject(s) - isocitrate lyase , acetone , inducer , chlorella , chemistry , enzyme , enzyme inducer , induction period , cell culture , biochemistry , chromatography , microbiology and biotechnology , biology , glyoxylate cycle , algae , botany , catalysis , genetics , gene
Isocitrate lyase (ICL) of Chlorella was induced with acetate, and induction kinetics followed in autospores and 6 h old cells of a synchronous culture. The enzyme could not be induced in illuminated cells. With both cell types 1.2 m M acetate was the optimal inducer concentration. Freeze‐thawed cells and acetone powders were used for measurement of activity. With the former the time course of increase in activity was different at the two cell ages. With 6 h old cells the activity fluctuated: There was first a period of increase, then one with decrease and again one of increase. No such variation was found with freee‐thawed autospores or with acetone powders of both cell stages. Darkening 6 h old cells for different periods of time before induction reduced the peak of activity, leaving the rate of the third phase unchanged. Illumination of darkened cells before induction increased the peak. Increasing the duration of both treatments increased their respective effects. Acetone extracts taken at different times after start of induction inhibited the ICL activity of a test preparation. The inhibition decreased concurrently with the variation in the ICL activity‐found‐when freee‐thawed cells were used in the enzyme assay. The inducibility, taken as the rate of the third phase, was measured at different times during the 24 h synchronous cycle. Using three different acetate concentrations and both methods of cell preparation, we found that the inducibility was constant for 17 h whereafter it increased rapidly to a final level.