The penicillins are a class of antibiotics containing two heterocyclic rings that interfere with the construction of cell walls by bacteria (Chemical Highlight 20-2). The interference results from reaction of the penicillin with an amino group of a protein that closes gaps that develop during construction of the cell wall. The insides of the cell leak out, and the organism dies. 

(a) Suggest a reasonable product for the reactions of penicillin G with the amino group of a protein (protein – NH₂). 

(b) Penicillin-resistant bacteria secrete an enzyme (penicillinase) that catalyzes hydrolysis of the antibiotic faster than the antibiotic can attack the cell-wall proteins. Propose a structure for the product of this hydrolysis and suggest a reason why hydrolysis destroys the antibiotic properties of penicillin. 

Transcribed Image Text:

H C,H5CH,CN CH Protein-NH, "CH3 H a "penicilloyl" protein derivative H CO,H Penicillin G