Purification and Biochemical Characteristics of Pectinesterase from Malatya Apricot (Prunus armeniaca L.)

Abstract

Pectinesterase (PE) in Malatya apricot pulp (Prunus armeniaca L.) was extracted and purified through (NH₄)₂SO₄ precipitation, dialysis, and DEAE-Sephadex gel filtration chromatography. The samples obtained from the dialysis procedure, named partially purified enzyme, were used for characterization of the apricot pectinesterase. The effect of various factors such as pH, temperature, heat, and storage stability on the partially purified apricot PE enzyme was investigated. Optimum pH value was 9.0 for PE with 1% pectin in 0.1 N NaCl (w/v). The optimum temperature for apricot PE was found to be 60°C on standard analysis conditions. Heat inactivation studies showed a decrease in enzymatic activity at temperatures above 70°C. Km and V_max values were 0.77 mM and 1.75 µmol min⁻¹ mg⁻¹ for apricot PE. Five inhibitors were tested in the study; the most effective inhibitor was found to be sodium carbonate (100% inhibition). The order of inhibitory effectiveness was: Na₂CO₃, iodine, lauril sulphate, AgNO₃, EDTA. Thermal inactivation data indicated that apparent activation energy with pectin substrate was 2.96 kcal mol⁻¹ for the enzyme. Ascorbic acid, CaCl₂, and KCl showed activatory effect on the apricot PE enzyme.

Keywords:

• Apricot
• heat stability
• isolation
• kinetic characterization
• pectin
• pectinesterase
• purification

ACKNOWLEDGMENT

The authors most gratefully acknowledge to State Planning organization (DPT) Research Fund for the financial support of this work (Project number 98 K-120830).