The process of induction of tryptophan oxygenase in Pseudomonas acidovorans is typical of many microbial enzyme induction systems, in that it (i) requires cell multiplication and de novo protein synthesis, (ii) is subject to catabolite repression, (iii) results in the formation of a stable enzyme, whose level, upon removal of inducer, is diluted out by cell proliferation, and (iv) exhibits prod...

There have been no reports of the quantitative prediction of induction for drug-metabolizing enzymes in humans. We have tried to predict such enzyme induction in humans from in vitro data obtained using human hepatocytes. The in vitro and in vivo data on enzyme induction by inducers, such as rifampicin, phenobarbital and omeprazole, were collected from the published literature. The degree of en...

Glutamine synthetase activity in Chinese hamster cells in tissue culture possesses properties identical with purified liver glutamine synthetase. The cellular level of enzyme is regulated by the concentration of glutamine in the growth media. Induction by removal of glutamine leads to an 8to IO-fold increase in enzyme activity within 48 hours. Repression is a much more rapid process. Half of th...

Catecholamines induced an increase in the activity of rat adipose tissue and liver phosphopyruvate carboxylases that was maintained for 48h. The response of adipose tissue phosphopyruvate carboxylase was blocked by actinomycin D, corticosteroids and propranolol, whereas corticosteroids and propranolol did not affect the liver enzyme. Cortisol phosphate, like actinomycin D, interfered only with ...

To determine the inducer(s) of the biodegradative threonine deaminase in Escherichia coli, the effects of various amino acids on the synthesis of this enzyme were investigated. The complex medium used hitherto for the enzyme induction can be completely replaced by a synthetic medium composed of 18 natural amino acids. In this synthetic medium, the omission of each of the seven amino acids threo...

The spermine analog N1,N11-diethylnorspermine (DE-333, also known as DENSPM or BENSPM) is regarded as the most potent known inducer of the polyamine catabolic enzyme, spermidine/spermine N1-acetyltransferase (SSAT), increasing activity by more than 200- to 1000-fold in certain cell types. The relative ability of a series of eight systematically modified DE-333 analogs to affect SSAT expression ...