[puzzled]

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.

[Donaldson Tan]

the enzyme mechanism follows the lock-and-key hypothesis. i think you gotta examine the active site on the gangrene enzyme to see why it likes to attack the Y-site.

[puzzled]

Thanks!  I got the idea now!

[AWK]

Bacteria may produce many substances that inhibit auto-destruction

[Donaldson Tan]

alternatively, the enzyme that causes tissue destruction exists in its de-activated form inside the bacteria. it requires a co-enzyme to activate it before it can attack its specific amino acid residual site. the co-enzyme and enzyme are most probably stored in different vesicles in the bacteria before both are released (secreted) together into the host body.

btw this seems more like a biology question. i will move it to the "chemical biology" section.