MadSci Network: Biochemistry

Re: What makes enzymes 'live'?

Date: Tue Nov 23 04:02:47 1999
Posted By: Melanie Stegman, Grad student, Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati
Area of science: Biochemistry
ID: 942356061.Bc

Dear Dillon,
Cool idea.  Well, to start, none of those ingredients are enzymes.  They 
are all smaller, organic molecules like detergents and some oils.  There 
could be some minor component of the conditioner that is not listed.  For 
example, a plant extract could be an ingredient.  That would basically be 
some leaves ground up into liquid and added to the conditioner.  If you 
grind up the leaves (or any plant or animal tissue) and then spin them in a 
centrifuge the large heavy parts, like the cell membranes and cell 
walls, settle to the bottom.  The top will be all the enzymes and other 
proteins and molecules that are the water soluble fraction of the cells.  
If you keep this preparation under nice conditions (basically the same 
conditions it was used to in the cell:  150 mM salt, 25 degrees C ...)  
then the enzyme may stay "live."

"Live" means that the enzyme still has activity.  Every enzyme has a 
specific task in the cell.  Enzymes catalyze reactions.  "Catalyze" means 
enzyme helps the reaction occur faster that it would normally.  Like when 
you introduce two people at a party...  those two people may have met 
without you, but by introducing them you have catalyzed their relationship.
The past answers I've included below are about catalase.  Catalase is an 
enzyme.  It catalyzes the reaction of H2O2 to H2O + O2.  Catalase will only 
catalyze that reaction, and no other enzyme will.  Any enzyme that does 
cause H2O2 to become H2O will be called a catalase.  This is because 
enzymes are named for their activity.
To know if your enzyme is "alive" you need to know the enzyme's activity.  
Then you need an assay for that enzyme's activity.  Then you need to show 
that when you add the enzyme to your test tube you see the activity and 
when you do not add the enzyme, you see no activity.  For example.  
Catalase catalyses the H2O2 to H2O reaction.  You could put H2O2 in two 
test tubes.  (hydrogen peroxide = H2O2)  You could add catalase to one 
tube, and nothing to the other.  After a few minutes you could show that 
there is less hydrogen peroxide in the tube with the enzyme added.  (Some 
chemicals have a colored reaction with H2O2 that would quantify the amnount 
of H202, for example.

You should do a similar thing.  Find out which enzymes the company claims 
to have in their conditioner.  You should get the full name. You should 
also be able to get from them the assay they use to measure the activity of 
that enzyme.  They should be able to tell you if the enzymes come from 
plants or animals...   I would call the company.

Here are some previous questions and answers to Mad Scientist that you 
might find helpful.  You should getting a college level cell biology 
textbook.  Look up enzyme in the index in the back.  A first year biology 
book would be ideal for these kinds of questions.  A great one I've read 
over and over again is The World of the Cell, by Wayne Becker.  

Remember when you read that book, when you read this answer and when you 
read any informative texts...  read them over several times!  I am giving 
you a lot of information, so does that college book.  No one can get it all 
the first time. Read what you can and then go back and read it again.

Good luck.  Enzymes are cool and interesting things!  They are not really 
"alive" but we would not be without them!

See ya,


Date: Sun Jul 19 17:46:05 1998
Posted By: Eric Maass, Operations Manager, semiconductors / communication 
Area of science: Biochemistry
ID: 898099328.Bc 


Re: How does the concentration of hydrogen peroxide affect the reaction...

Date: Sun Jul 19 17:46:05 1998
Posted By: Eric Maass, Operations Manager, semiconductors / communication 
Area of science: Biochemistry
ID: 898099328.Bc 


Hello, Edgella -- your question took me back to my master's thesis (I 
worked on developing a glucose sensor, involving glucose oxidase and 
catalase)......anyway, to answer your question:

The rate of the catalase reaction follows one of the general equations for 
enzyme-catalyzed reactions, the Michaelis-Menten equation.  The rate of the 
catalase reaction with hydrogen peroxide would be:

reaction rate V = 

    Vmax x [Concentration of hydrogen peroxide]
     Km + [Concentration of hydrogen peroxide]

Vmax is the maximum reaction rate. 
Km is the Michaelis-Menten constant, and for catalase, Km = 25mM (25 

Basically, the Michaelis-Menten equation reflects the fact that the 
reaction rates for enzymic reactions saturate -- that is, they reach a 
maximum reaction rate (Vmax), and stay at that maximum reaction rate 
regardless of how much additional hydrogen peroxide you add beyond that 

You should be able to plot what this graph should look like, for various 
amounts of hydrogen peroxide -- hopefully, the 
time that the disc takes to rise from the bottom of a beaker full of 
various concentrations of hydrogen peroxide should correspond to the 
reaction time, and therefore with the reaction rates.

Good luck! And happy experimenting!

Date: Wed Dec 2 17:20:23 1998
Posted By: Homero Rey, Sr. Application Scientist
Area of science: General Biology
ID: 912549344.Gb 


The following paragraph is from an enzyme web site 
( but it 
explains the relationship between enzyme activity and temperature very 

   All chemical reactions speed up as temperature is raised. As the 
temperature increases, more molecules have enough kinetic energy to undergo 
the reaction. Since enzymes are catalysts for chemical reactions, enzyme 
reactions also tend to proceed faster with increasing temperature. However, 
if the temperature of an enzyme-catalyzed reaction is raised still further, 
an optimum is reached: above this point, the kinetic energy of the enzyme 
and water molecules is so great that the structure of the enzyme molecules 
starts to be disrupted. The positive effect of speeding up the reaction is 
now more than offset by the negative effect of denaturing more and more 
enzyme molecules.  Many proteins are denatured by temperatures around 
40-50deg.C, but some are still active at 70-80deg.C, and a few even 
withstand being boiled.

   Different enzymes have different optimum temperatures, depending on the 
organism and environment they have evolved in.  The same enzyme can also 
have different optimum temperatures depending on it's source.  As an 
example, I found the following reference for a plant catalase that has an 
optimum temperature of 40 deg. C and an operating range of 0-50 deg. C.  

TITLE:  One-step purification and properties of catalase from leaves of 
Zantedeschia aethiopica.

AUTHORS: Trindade H; Karmali A; Pais MS

AUTHOR AFFILIATION: Falcudade de Ciencias de Lisboa, Departamento de 
Biologica Vegetal, Lisbon, Portugal.

SOURCE: Biochimie 1988 Dec;70(12):1759-64

ABSTRACT: Catalase (E.C was purified from leaves of Zandedeschia 
aethiopica to apparent hmogeneity by a one-step hydrophobic interaction 
chromatography on a phenyl Sepharose CL-4B column. The purified enzyme 
preparation was obtained with a final recovery of enzyme activity of about 
61% and a specific activity of 146 U/mg protein. The purified enzyme ran as 
a single protein band when analyzed both by native PAGE and SDS-PAGE 
corresponding to an Mr of 220,000 Da, which consists of 4 subunits with 
identical Mr of 54,000 Da. The pI of purified enzyme was found to be 5.2 by 
isoelectric focusing on ultrathin polyacrylamide gels. The purified 
catalase has an optimum temperature of activity at 40 degrees C, whereas it 
is stable between 0 degrees and 50 degrees C. As regards pH, the enzyme has 
an optimum activity at pH 7.0 and it is stable in the range pH 6-8. The 
absorption spectrum of the purified enzyme exhibited 2 peaks at 280 nm and 
405 nm.


  So there is no single answer to your question!  Depending on the 
particular catalase you're interested in, you will find different optimum 
  Hope this helps!

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