catabolite repression


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ca·tab·o·lite re·pres·sion

the decreased expression of an operon because of elevated levels of a catabolite of a biochemical pathway.

catabolite repression

REPRESSION of certain INDUCIBLE ENZYME systems by the presence of specific carbon sources, such as GLUCOSE, that the organism prefers to metabolize. For example, in bacteria, EXPRESSION of the LAC OPERON, concerned with the enzymes for the breakdown of LACTOSE, is repressed in the presence of glucose, even though inducers of the operon are available. When the glucose is used up, expression of the lactose operon can be induced. Catabolite repression is important to the efficient running of the cell, because glucose can be metabolized directly in GLYCOLYSIS without the need to expend energy inducing the synthesis of those enzymes required to metabolize the lactose. See also OPERON MODEL.
References in periodicals archive ?
Furthermore, pseudo-continuous fermentation in the co-culture system allows us to use a wide range of dilution rates and to prevent the diauxic kinetics caused by the xylose catabolite repression associated with S.
Below 25[degrees]C enzyme activity was less due to inappropriate incubation temperature for yeast growth, and at high temperature results in less enzyme production due to catabolite repression of enzyme (Gomez et al.
This study documents catabolite repression of prodigiosin synthesis, motility, and antibiotic susceptibility properties based upon different sugar supplemented growth conditions using S.
The decreased activity in the later phase of growth was probably due to catabolite repression by glucose released from starch hydrolysis.