Beta-lactam antibiotics amoxicillin/ampicillin

The first studies in enzyme engineering examined the effects of mutations on enzyme active sites. Beta-lactamase, the enzyme used by bacteria to degrade beta-lactam antibiotic (penicillin, ampicillin, and amoxicillin) was one of the first enzymes examined... 

Since beta-lactam antibiotics also appear to be associated with pemphigus, especially ampicillin and amoxicillin, an earlier hypothesis (SEDA-5, 244) that this (and perhaps other reactions) to beta-lactam antibiotics may in fact be induced by the hydrolytic metabolite penicillamine has received attention (280,283). 

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