Characterization of α-amylases Isolated from Cyperus esculentus Seeds (tigernut): Biochemical Features, Kinetics and Thermal Inactivation Thermodynamics

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dc.contributor.authorAvwioroko, Oghenetega
dc.date.accessioned2022-09-15T12:14:20Z
dc.date.available2022-09-15T12:14:20Z
dc.date.issued2019
dc.description.abstractIn this study, α-amylases from fresh and dried Cyperus esculentus seeds were isolated and characterized for biochemical and thermodynamic properties. The α-amylases (FTNE-α-amylase and DTNE-α-amylase) were optimally active at 60–70 oC, pH 7.0 (FTNE-α-amylase) and pH 6.0 (DTNE-α amylase) with activation energies (Ea) of 3.56 and 6.81 kJ mol-1, respectively. Both enzymes retained above 70% of their hydrolytic activities after 1 h at pH 6.0–8.0. The enzyme activities were more enhanced in the presence of divalent metal ions (Ca2+, Mg2+, Zn2+, Cu2+, Ba 2+, Co2+, Pb2+, and Hg2+) than monovalent ions. SDS, cyclohexanol, ether and diethylamine inhibited them except EDTA. Using soluble starch as substrate, DTNE-α-amylase had higher Vmax, Kcat and lower Km than FTNE-α-amylase. Both enzymes expressed high substrate preferences for yam flour amidst other substrates with catalytic efficiencies (Kcat/Km) of 2.71 and 4.44 mL. mg respectively. The higher catalytic efficiency of DTNE-α amylase was due to its transition state stabilization (ΔGE-S ¼ -0.90 kJ mol-1 and ΔGE-T ¼ - 2.22 kJ mol-1). Fourier Transformed-Infrared (FTIR) spectroscopy revealed changes in C–O stretching and -N-H bending in the substrate-bound enzymes. Thermal inactivation of the amylases followed first-order rate kinetics and was non-spontaneous (ΔG#>0). FTNE-α-amylase half-lives and D-values at 70 and 80 oC, and Z-value (256.41oC), were however higher than in DTNE-α-amylase (Z-value ¼ 63.29 oC; t1/2 ¼ 22.43 min at 70oC) indicating that FTNE-α-amylase is more thermally stable than DTNE-α-amylase and would be more industrially applicable as a thermostable starch-hydrolyzing enzyme.en_US
dc.identifier.issnhttps://doi.org/10.1016/j.bcab.2019.101298
dc.identifier.urihttp://dspace.run.edu.ng:8080/jspui/handle/123456789/3632
dc.language.isoenen_US
dc.publisherELSEVIER Biocatalysis and Agricultural Biotechnologyen_US
dc.subjectCyperus esculentus seedsen_US
dc.subjectα-amylaseen_US
dc.subjectCharacterisationen_US
dc.subjectKineticsen_US
dc.subjectThermal stabilityen_US
dc.subjectThermodynamicsen_US
dc.titleCharacterization of α-amylases Isolated from Cyperus esculentus Seeds (tigernut): Biochemical Features, Kinetics and Thermal Inactivation Thermodynamicsen_US
dc.typeArticleen_US
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