A comparison of thermal characteristics and kinetic parameters of trehalases from a thermophilic and a mesophilic fungus

Bharadwaj, Girish and Maheshwari, Ramesh (1999) A comparison of thermal characteristics and kinetic parameters of trehalases from a thermophilic and a mesophilic fungus. In: FEMS Microbiology Letters, 181 (1). pp. 187-193.

PDF A_comparison_of_thermal_characteristics.pdf Restricted to Registered users only Download (214kB) | Request a copy

Abstract

Trehalases from a thermophilic fungus Thermomyces lanuginosus $(M_r \hspace{2mm} 145 \hspace{2mm} kDa)$ and a mesophilic fungus Neurospora crassa $(M_r \hspace{2mm} 145 \hspace{2mm} kDa)$ were purified to compare their thermal characteristics and kinetic constants. Both trehalases were maximally active at $50^oC$, had an acidic pH optimum and were glycoproteins (20% and 43%, w/w, carbohydrate content for T. lanuginosus and N. crassa, respectively). At their temperature optimum, their Km was similar (0.57 and 0.52 mM trehalose, for T. lanuginosus and N. crassa, respectively) but the $V_{max}$ of N. crassa enzyme was nine times higher than of T. lanuginosus enzyme. The catalytic efficiency, $k_{cat}/K_m$, for N. crassa trehalase was one order of magnitude higher $(6.2 \times 10^6 M^{-1} s^{-1})$ than of T. lanuginosus trehalase $(4 \times 10^5 M^{-1} s^{-1})$. At their Topt (50°C), trehalase from both sources exhibited similar thermostability $(t_{1/2}>6 h)$. The energy of activation, $E_a$, for T. lanuginosus trehalase was 15.12 kcal $mol^{-1}$ and for N. crassa trehalase it was 9.62 kcal $mol^{-1}$. The activation energy for thermal inactivation for the N. crassa enzyme $(92 \hspace{2mm}kcal \hspace{2mm} mol^{-1})$ was two-fold higher than for the T. lanuginosus enzyme $(46 \hspace{2mm}kcal\hspace{2mm} mol^{-1})$. The present study shows that the trehalase of N. crassa is not only more stable but also a better catalyst than the T. lanuginosus enzyme.

Item Type:	Journal Article
Publication:	FEMS Microbiology Letters
Publisher:	Elsevier
Additional Information:	Copyright of this article belongs to Elsevier.
Keywords:	Trehalase;Thermophilic fungus;Mesophilic fungus;Thermomyces lanuginosus;Neurospora crassa
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	28 Sep 2007
Last Modified:	19 Sep 2010 04:39
URI:	http://eprints.iisc.ac.in/id/eprint/11953

Actions (login required)

View Item