An unusual thermostable aspartic protease from the latex of Ficus racemosa (L.).

Devaraj, K. B. and Gowda, L. R. and Prakash, V. (2008) An unusual thermostable aspartic protease from the latex of Ficus racemosa (L.). Phytochemistry, 69 (3). pp. 647-55. ISSN 0031-9422

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Abstract

The most extensively studied ficins have been isolated from the latex of Ficus glabrata and Ficus carica. However the proteases (ficins) from other species are less known. The purification and characterization of a protease from the latex of Ficus racemosa is reported. The enzyme purified to homogeneity is a single polypeptide chain of molecular weight of 44,500+/-500Da as determined by MALDI-TOF. The enzyme exhibited a broad spectrum of pH optima between pH 4.5-6.5 and showed maximum activity at 60+/-0.5 degrees C. The enzyme activity was completely inhibited by pepstatin-A indicating that the purified enzyme is an aspartic protease. Far-UV circular dichroic spectra revealed that the purified enzyme contains predominantly beta-structures. The purified protease is thermostable. The apparent T(m), (mid point of thermal inactivation) was found to be 70+/-0.5 degrees C. Thermal inactivation was found to follow first order kinetics at pH 5.5. Activation energy (E(a)) was found to be 44.0+/-0.3kcal mol(-1). The activation enthalpy (DeltaH *), free energy change (DeltaG *) and entropy (DeltaS *) were estimated to be 43+/-4kcal mol(-1), -26+/-3kcal mol(-1) and 204+/-10cal mol(-1)K(-1), respectively. Its enzymatic specificity studied using oxidized B chain of insulin indicates that the protease preferably hydrolyzed peptide bonds C-terminal to glutamate, leucine and phenylalanine (at P1 position). The broad specificity, pH optima and elevated thermal stability indicate the protease is distinct from other known ficins and would find applications in many sectors for its unique properties.

Item Type:	Article
Uncontrolled Keywords:	Ficus racemosa; Moraceae; Aspartic protease; Plant proteases; Endopeptidases; Ficin
Subjects:	500 Natural Sciences and Mathematics > 10 Plants 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 16 Enzyme Chemistry
Divisions:	Protein Chemistry and Technology
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	19 Aug 2008 07:06
Last Modified:	05 Dec 2016 10:45
URI:	http://ir.cftri.res.in/id/eprint/1831

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