Re: How do the enzymes in stain removers work?

Eleanor,
     The enzymes in stain removers are members of the enzyme family called 
proteases.  These enzymes digest proteins by cleaving the amide bonds that 
hold together the individual amino acids that make up the protein.  
Individual amino acids (or short chains of them) are fairly water soluble.  
However proteins, which are composed of a great many amino acids joined 
together, are much less water soluble.   This makes them difficult to wash 
out of clothing with just soap and water.  The enzymes decompose the 
protein, thereby converting it into components that can be removed with 
soap and water. 

Proteases can also cleave ester bonds, which are the type of chemical bonds  
in fats and oils.  So, these enzymes probably can also help remove stains 
left by members of this chemical family as well, which includes grease.

In addition to monitoring the amounts of enzymes in different cleaners, you 
should also note if the package tells what the name of the enzyme is.  
There are several of these enzymes, and they differ in their activities and 
in their tolerance of high temperature (which will be important if you wash 
in hot water!).