Gas gangrene is caused by the anerobic bacteria, Clostridium perfringens. This bacteria causes massive tissue destruction. One of the enzymes that it secretes cleaves preferentially at the Y-Gly bond in the sequence Proline-Tyrosine-Glycine-Proline, where Tyrosine is most frequently a neutral amino acid.
P-Y-G-P- -----> -P-Y-COO(-) + (+)NH3-G-P-
Propose why the enzyme doesn't affect the bacteria itself. I'm thinking...because the enzyme doesn't lose any atoms? I have no idea, and the websites I find only explain about gas gangrene itself and doesn't lead me to an answer.