One of the commenters on a previous post, pointed out that proteases have pretty diverse structures, even though they also share a common function.
What else could I do? I had to take a look. I found structures for chymotrypsin (from a cow) and subtilisin (from a soil bacteria, Bacillus lentus) and used Cn3D to see how they compare (below the fold).
Both enzymes are proteases - that is they cut the peptide bonds in proteins that hold amino acids together. Many of you use proteases routinely, without knowing it or probably even thinking about it. Proteases, including subtilisin have been used in laundry detergent, for over 35 years (1). We also use proteases in meat tenderizer, though this is mostly a different protease, papain.
Chymotrypsin and subtilisin both like to cut proteins on the carboxyl side of large aromatic residues like tryptophan, tyrosine, and phenyalanine. They aren't identical in terms of specificity, though. Subtilisin is less fussy and will digest a wider variety of proteins (2). This characteristic might explains why it's widely used in laundrey detergent.
As you can see below, somnilista is right. The structures are pretty different. Maybe, I'll look into this a bit more when I'm less strapped for time.
The brown arrows show beta sheets, and the green cones, alpha helices. You can see that chymotrypsin has far more beta sheets and fewer helices than subtilisin.
If you want to take a look for yourself, the links are below. Click the View 3D Structure button to download the structure files. If you don't have the viewing program (Cn3D), there are links to download it from the same page.
References:
1. A quick PubMed search for proteases and laundrey detergent.
2. the Sigma Aldrich catalog. References for subtilisin and chymotrypsin.
technorati tags: digital biology,
biotechnology, proteases, molecular modeling, Cn3D,
molecular structures
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The similar function of chymotrypsin and subtilisin is considered a classic example of convergent evolution. This is probably mentioned in every biochemistry textbook. Mine is Stryer (2 ed).
For use in a laundry detergent, you want something that stores well and works in hot water. I would guess the detergent companies looked into extremophiles for good candidates. Let natural selection do the work for you.
Yeah, as I was writing this, I remembered that this was a favorite subject in my biochemistry courses.
I heard Jody Deming talk a few years ago at the UW. Detergent companies are still looking into extremophiles, especially the psychrophiles since those enzymes work well with a cold water wash.
Apparently putting enzymes in consumer products requires some caution with respect to allergenicity. I happened across this:
HLA-DQ8 is a predisposing molecule for detergent enzyme subtilisin BPN'-induced hypersensitivity.
Xue A, Chapoval SP, Finn ES, Chowdhary VR, Marietta EV, Gaffey TA, Pursifull AC, David CS.
Clin Immunol. 2005 Dec;117(3):302-15. Epub 2005 Sep 26.
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Here's a patent for specific use of subtilisin in detergent. Here's another patent.
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Modification of subtilisin for use in detergent
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This stuff is big business.