1. Penicillin

2. 1928: Alexander Fleming noticed that a mould (penicillium notatum) produced a compound that inhibits bacterial growth. 1940: Florey and Chain showed that an injection of extract cured infections in mice and later in humans. 1945: Fleming, Florey and Chain were awarded a Nobel Prize for Medicine.

4. Penicillin-G

5. Penicillin works by inhibiting an enzyme involved in the building of bacterial cell walls.

6. The mould extract was broken down if taken by mouth and effective only against a limited range of bacteria. In the 1950s it was shown that penicillin-G could be broken down to give 6-amino penicinillic acid from which a range of semi- synthetic penicillins could be made.

7. 6-APA

9. Unfortunately penicillins are fragile What is the bond angle here ? What does it “want” to be ? How can it get there ?

10. Bacteria that have the enzyme β-lactamase can hydrolyse the strained amide group. These are resistant. Suggest 2 ways of overcoming this resistance. Why does this resistance spread?

11. 1)Make a penicillin that does not fit into the active site of β-lactamase : Methacillin 2) Inhibit β- lactamase by mixing the active penicillin with Clavulanic acid