MadSci Network: General Biology

Re: What is the optimum temperature of the enzyme catalayse?

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!

Current Queue | Current Queue for General Biology | General Biology archives

Try the links in the MadSci Library for more information on General Biology.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-1998. All rights reserved.