African Journal of
Biochemistry Research

  • Abbreviation: Afr. J. Biochem. Res.
  • Language: English
  • ISSN: 1996-0778
  • DOI: 10.5897/AJBR
  • Start Year: 2007
  • Published Articles: 425

Full Length Research Paper

Influence of CaCl2 and EDTA on reversible thermal inactivation of recombinant wild-type and mutant (E40H/E44H) Phlebia radiata manganese peroxidase 3 (rPr-MnP3)

Usenobong F. Ufot*
  • Usenobong F. Ufot*
  • Department of Chemistry and Biochemistry, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, U. K.
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Monday I. Akpanabiatu
  • Monday I. Akpanabiatu
  • Department of Biochemistry, Faculty of Basic Medical Sciences, College of Health Sciences, University of Uyo, P. M. B. 1017, Uyo, Nigeria.
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  •  Received: 22 June 2014
  •  Accepted: 10 August 2014
  •  Published: 15 August 2014


Thermal inactivation of a new recombinant Phlebia radiata manganese peroxidase (rPr-MnP3) in the presence and absence of additives (CaCl2 and EDTA) is described for the first time. The influence of temperature and melting points (Tm) on the stability of rPr-MnP3 and its mutant (E40H/E44H) were determined. There was no significant inactivation at 25 – 40°C. However, we observed rapid inactivation of rPr-MnP3 at 50°C and above. Addition of CaCl2 to the enzyme mixture resulted in a marked increase in the half-life (533 min) of the wild-type enzyme compared to E40H/E44H with the half-life of 92 min. Ethylenediaminetetraacetic acid (EDTA) increased the rate of rPr-MnP3 thermal inactivation as shown by the decay constant (kd) of 0.070 ± 0.007 min-1 and half-life of 10 min. The decay constant (kd) 0.029 ± 0.002 min-1 and half-life of 24 min were obtained for the control (untreated sample). Calcium ion had protective effect on the inactivation of the wild-type enzyme but not for mutant. The mutant (E40H/E44H) was observed to be more stable with a higher melting point of 58°C than the wild-type (Tm =54°C).The inactivation effect of EDTA on the E40H/E44H was lower than that of the wild-type. Calcium ions were found to be important structural elements responsible for the enzyme stability. Our findings showed that rPr-MnP3 is a highly stable enzyme and may be of significant industrial applications.   

Key words: Peroxidase, Phlebia radiata, thermal stability, thermal inactivation, reactivation, melting point, additives.