Enzymes help speed and increase the performance of cleaning products. Most consumer laundry detergents contain enzymes to help remove stains, increase whiteness, eliminate fabric pills, and prevent resoiling. The inclusion of enzymes in laundry detergents also allows for shorter wash cycles and lower wash temperatures while ensuring the desired cleaning result, thus, providing energy savings. 
Detergents contain different enzymes to target different stains, they are substrate specific, targeting a specific active site, activate, then wash away.
Proteases break down proteins, eg. blood, egg, gravy, and other protein stains.
Amylases break down starches, and lipases break down fats and grease. 
Cellulases contribute to overall fabric care by rejuvenating or maintaining the new appearance of washed garments. 
Enzymes have been used in laundry products since the 1950’s, are extremely carefully formulated, effective, safe and do not cause skin reactions .
For more information on what is in detergents and the function of the raw materials see The Wash Wise Detergent Ingredients Info Sheet.
 http://link.springer.com/article/10.1007/s11743-998-0058-7 [The role of enzymes in modern detergency]
 http://www.medscape.com/viewarticle/575890 [Enzymes, Detergents and Skin: Facts and Fantasies]