結核菌に対するRifampicinの作用機序

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Purified DNA-dependent RNA polymerase was prepared from BCG and the inhibition of RNA polymerase activity by rifampicin was observed. Uptake of 14C-rifampicin by M. phlei sensitive and resistant to rifampicin was studied. Purified DNA-dependent RNA polymerase was obtained as follows: 70g of BCG were disrupted by Ribi cell-fractionator, and the homo genates were centrifuged succesively at 70, 000×g for 40 minutes and then 240min. The supernatant was centrifuged at 105, 000×g for 10hours. The sediment was adsorbed to DEAE- cellulose column and the eluate was fractionated by ammonium sulfate precipitation. Then the enzyme was purified further by a linear glycerol density gradient. M. phlei strains sensi tive or resistant to rifampicin cultured on Sautons liquid medium were suspended in Dubos liquid medium and 14C-rifampicin was added to give a final concentration of 10mcg/ml. Uptake of 14C-rifampicin by cells were measured. Rifampicin inhibited purified DNA-dependent RNA polymerase activity obtained from BCG cells. Nearly 70% of activity was inhibited by 0.1 mcg/ml of rifampicin. The increase in the concentration of rifampin to 1.0mcg/ml did not affect much in the inhibition of RNA polymerase. Rifampin did not affect the chain elongation on RNA synthesis but inhibited the chain initiation in RNA synthesis in BCG. In rifampin resistant strain of M. phlei, 14C-labeled rifampin was taken up somewhat less degree than sensitive strain. The mode of mechanism of resistance seemed not by cell wall permeability change but by the change of enzyme conformation of RNA polymerase.
日本結核病学会の論文

結核菌に対するRifampicinの作用機序

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