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Problem: Subtilisin is inactivated by bleach (peroxide) in laundry
This is due to oxidation of active site residue Met-222 & the formation of
methionine sulfoxide. Oxidized Met interferes with important reactive residues. Enzyme Kinetics!
Case Study - Genetic Engineering of
Solution: Use genetic engineering (site-directed mutagenesis) to
replace Met-222 with another residue that does not react with peroxide yet
P enzyme of function.
still allows the roductionto a n Oxidatively Resistant Subtilisin
F IG. 1. Stereoscopic view of t he
active site of subtilisin from B . a m- \ kc/ yloliquefaciena s tructure (Wright et
a l.. 1969). Residues labeled include NEED to put numbers to 32
serine 221, histidine 64, a nd aspartate
which form t he function to
enzyme catalytic triad typical of
serine proteases. Also labeled is methio222 which is t he residue identified
by peptide mapping studies t o be oxid f changing amino acyloized to the sulfoxide by HP02 with res ultant inactivation (Stauffer nd Etson,
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