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.