Subscribe Now Subscribe Today
Science Alert
 
Blue
   
Curve Top
Journal of Applied Sciences
  Year: 2013 | Volume: 13 | Issue: 6 | Page No.: 929-933
DOI: 10.3923/jas.2013.929.933
 
Facebook Twitter Digg Reddit Linkedin StumbleUpon E-mail

Properties of Phenoloxidases from the Tomato Leafminer, Tuta absoluta (Meyrick)
R. Tarek Amin, E. Takwa Ellakwa and E. Doha Ellakwa

Abstract: The kinetic properties of phenoloxidases system from the fourth larval instar of the tomato leafminer, Tuta absoluta (Meyrick) were studied to detect the optimum condition for phenoloxidases-catalyzed reaction. The results of phenoloxidases activity towards catechol at different pH values revealed that the optimum pH was 5.5. The phenoloxidases activity increased gradually from 15 to 35°C and began to decline that phenoloxidases lost 60.5% of their activity at 55°C. A period of only 2 min for the tomato leafminer phenoloxidases was found to fit well within the linear part of the enzyme activity curve. On the other hand, the oxidation was directly proportional to the substrate concentration up to 10-4 M, where the peak was reached. Using Lineweaver-Burk plot, it was found that Km (Michaelis constant) was 12.98 10-6 M, while Vmax (maximum velocity of the reaction) was 0.862 O.D. units/min/mg proteins. The relatively small Km value indicates that phenoloxidases can hydrolyze catechol efficiently, even at very low concentration. The significance of results and effect of organic solvents on phenoloxidases reaction were discussed. It could be concluded that 1 mL of the reaction mixture consists of 5 μg sample protein and 0.1 mM catechol in 0.1 M phosphate buffer (pH 5.5) at 25°C for 2 min, represents the optimum condition for T. absoluta phenoloxidases system activity.
PDF Fulltext XML References Citation Report Citation
How to cite this article:

R. Tarek Amin, E. Takwa Ellakwa and E. Doha Ellakwa, 2013. Properties of Phenoloxidases from the Tomato Leafminer, Tuta absoluta (Meyrick). Journal of Applied Sciences, 13: 929-933.

DOI: 10.3923/jas.2013.929.933

URL: https://scialert.net/abstract/?doi=jas.2013.929.933
COMMENT ON THIS PAPER
 
 
 

 
  Bullet Navigation
 
  Page Icon Online First
  Page Icon Current Issue
  Page Icon Previous Issues
  Page Icon Editorial Board
  Page Icon Submit a Manuscript
  Page Icon Guide to Authors
  Page Icon Subscribe to E-alerts

  Bullet Indexed In
 
  Page Icon AGRIS
  Page Icon ASCI-Database
  Page Icon Asian Digital Library
  Page Icon Chemical Abstract Services
  Page Icon Google Scholar

Science Alert
Curve Bottom