Chloramphenicol selective enzyme inhibition

Becker and Hurwitz 94) have found that after infection of E. coli B with T-even bacteriophages a novel 3 -deoxynucleotidase activity appears. They purified the enzyme 2000-fold. In addition to its attack on 3 -deoxymononucleotides, the enzyme selectively removes the 3 -phos-phoryl groups from DNA. It does not attack 3 -ribonucleotides, 3 -phosphoryl groups of RNA, or 5 -phosphate esters. Like bacterial 5 -nucleotidases, this enzyme is markedly activated by Mg2+ and Co2+ and is inhibited by EDTA. The enzyme appears to be a phage-induced enzyme the activity rises early after injection with T-even phages and formation of the enzyme is blocked with chloramphenicol. 

Mechanism-based irreversible inhibition occurs when a reactive metabolic intermediate is formed in situ that can (1) bind covalently with the prosthetic heme through N-alkyllary-lation (e.g., secobarbital), f"2 alkylate the apo-cytochrome (e.g., chloramphenicol or 2-ethy-nylnaphthalene), or (5) cause destruction of the prosthetic heme to products that irreversibly bind to the apocytochrome (e.g. CCI4) (158). These mechanism-based inactivators have primarily been designed and used for the selective inhibition of specific CYP enzymes and elucidating the mechanism of P450 reactions. Some drugs (e.g., aromatase inhibitors)... 

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