The penicillin's action to block the transpeptidase enzyme in bacteria is as a competitive inhibitor of this enzyme.
I hope this helps.
If you have further questions then let me know and I will be happy to get back with you.
Anthony Bray MD
Well I looked it up in an old text of mine >>
Basic and Clinical Pharmacology (forth edition)
I looked up a web article reference that covers the point although it discusses a new drug that is related to the penicillins.
This article may be found at:
If you look up this then click Pharmacology and mechanism of Action. About three lines down it states "B lactam antibiotics mimic the substrate for PBP"
Penicillin is a beta lactam antibiotic and PBP stands for penicillin binding protein.
The point is that if the penicillin mimics the substrate then it is competing with that substrate for the site on the enzyme.
I hope this helps. Let me know if you have further questions.