Antibiotics derivable from single amino acids

The penicillins (pen-uh-SILL-ins) are a class of antibiotic compounds derived from the molds Penicillium notatum and Penicillium chryAogenum. The class contains a number of compounds with the same basic bicyclic structure to which are attached different side chains. That basic structure consists of two amino acids, cysteine and valine, joined to each other to make a bicyclic ( two-ring ) compound. The different forms of penicillin are distinguished from each other by adding a single capital letter to their names. Thus penicillin F, penicillin G, penicillin K, penicillin N, penicillin 0, penicillin S, penicillin V, and penicillin X. A number of other antibiotics, including ampicillin, amoxicillin, and methicil-lin, have similar chemical structures. 

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