Cyclic AMP transport across membrane vesicles of ultra-violet light irradiatedEscherichia coli |
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Authors: | D Bhatnagar A K Bhattacharya |
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Institution: | (1) Department of Biophysics, Institute of Medical Sciences, Banaras Hindu University, 221 005 Varanasi, India |
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Abstract: | Transport of cyclic AMP acrossEscherichia coli membrane was studied using membrane vesicles. Uptake of cyclic AMP was measured using normally oriented vesicles, whereas
uptake in everted vesicles was taken as a measure of the efflux of cyclic AMP. Ultra-violet irradiation of the cells led to
an inhibition of both uptake and efflux of cyclic AMP across the membrane. The presence of cyclic AMP in the growth medium
prior to ultra-violet irradiation caused an enhancement of the uptake and efflux. The uptake and efflux of cyclic AMP were
less in vesicles from glucose grown cells as compared to the uptake and efflux by the vesicles prepared from glycerol grown
cells. Similarly both uptake and efflux of cyclic AMP were more in vesicles prepared from cells grown on glycerol or glucose
in the presence of cyclic AMP than in vesicles from cells grown in absence of cyclic AMP. It is suggested that the number
of cyclic AMP carrier molecules were reduced in cells under catabolite repression by glucose as well as by ultra-violet irradiation |
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Keywords: | cyclic AMP transport membrane vesicles ultra-violet irradiation catabolite repression |
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