title: Purification and biochemical characterization of feruloyl esterases from Aspergillus terreus MTCC 11096.
abstract: Aspergillus terreus MTCC 11096 isolated from the soils of agricultural fields cultivating sweet sorghum was previously identified to produce feruloyl esterases (FAEs). The enzymes responsible for feruloyl esterase activity were purified to homogeneity and named as AtFAE-1, AtFAE-2, and AtFAE-3. The enzymes were monomeric having molecular masses of 74, 23 and 36 kDa, respectively. Active protein bands were identified by a developed pH-dependent zymogram on native PAGE. The three enzymes exhibited variation in pH tolerance ranging between pH 5-8 and thermostability of up to 55°C. Inhibition studies revealed that the serine residue was essential for feruloyl esterase activity; moreover aspartyl and glutamyl residues are not totally involved at the active site. Metal ions such as Ca(2+), K(+), and Mg(2+) stabilized the enzyme activity for all three FAEs. Kinetic data indicated that all three enzymes showed catalytic efficiencies (k(cat) /K(m)) against different synthesized alkyl and aryl esters indicating their broad substrate specificity. The peptide mass fingerprinting by MALDI/TOF-MS analysis and enzyme affinity toward methoxy and hydroxy substituents on the benzene ring revealed that the AtFAE-1 belonged to type A while AtFAE-2 and AtFAE-3 were type C FAE. The FAEs could release 65 to 90% of ferulic acid from agrowaste substrates in the presence of xylanase.
authors.affiliation: Chemical Biology Laboratory, Medicinal Chemistry and Pharmacology Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, Andhra Pradesh, 500007, India. cgkumar@iict.res.in
authors.forename: C Ganesh
authors.initials: CG
authors.lastname: Kumar
authors.forename: Avijeet
authors.initials: A
authors.lastname: Kamle
authors.forename: Ahmed
authors.initials: A
authors.lastname: Kamal
mesh_terms: D001230:Aspergillus / Q000201:enzymology* / Q000302:isolation & purification; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D002265:Carboxylic Ester Hydrolases; C070196:feruloyl esterase
keywords: Aspergillus terreus; characterization; feruloyl esterase; purification; substrate specificity