Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Removing Blood Stains
Name: Nelly
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: N/A 

Proteases are enzymes that are used in a washing powder to remove blood stains. Why people used proteases to remove blood stains instead of lipases or amylases? How do these enzymes removed those stains( the process ) ?

I am not a specialist on detergents and soaps but here is my understanding of this: The compound of a blood stain that causes the coloring is iron, bound in a protein called hemoglobin. It is this protein that gives blood its red color, and the iron ions captured in hemoglobin transport oxygen in our blood.

When blood dries up on cloth material, the protein becomes denatured (is no longer in the biologically active form) and binds to the material fibres. The iron (no longer bright red but ironish brown) is captured in this protein. Heating (hot washing) fixates the protein even stronger to the tissue. It can not be removed with normal soap which removes grease and fat, but poorly removes protein. Proteases degrade the protein into small bits that come loose, and then the iron ions (the color of the stain) are released. Lipases degrade fat and amylases degrade polysachharides, both would be useless to remove hemoglobin.

Trudy Wassenaar

Hemoglobin which is the bulk of the "blood stain" is a protein...proteases dissolve protein...lipases dissolve lipids (fats and oils) and amylases dissolve starch.

Peter Faletra Ph.D.
Office of Science
Department of Energy

Click here to return to the Molecular Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory