Purification and Characterization of Invertase From Dates (Phoenix Dactylifera L., Var. Zahdi)

Abstract

Zahdi dates (Phoenix dactylifera) contain invertase at all development stages; the highest specific activity is present in the late yellow stage. The enzyme was purified to homogeneity, as determined by disc gel electrophoresis and isoelectric focusing, by a combination of techniques including ammonium sulfate precipitation, DEAE‐cellulose chromatography and gel filtration on Sepharose 4B and Sephadex G‐150 columns. A complex of invertase with a high molecular weight pectic substance of the date could not be dissociated by ammonium sulfate or DEAE‐cellulose chromatography but the complex was dissociated by gel filtration on a Sepharose 4B column at pH 4.0 and ionic strength of 0.5 M. The enzyme contained 8.2% carbohydrate covalently linked probably via an amide linkage to aspartic acid. Molecular weight determination by exclusion gel chromatography and sedimentation equilibrium gave values of 130,000 and 97,100 ± 1,300, respectively. The enzyme is probably composed of two identical subunits as shown by SDS polyacrylamide gel electrophoresis. Amino acid analyses showed the enzyme to be low in sulfur‐containing amino acids. Date invertase is an acid β‐fructofuranosidase with a pH optimum between 3–4 and with a Km and kcat for sucrose of 6mM and 49 sec‐1, respectively. Activation energies for denaturation of enzyme and conversion of substrate to product were determined to be 48.7 and 17.6 kcal/mole, respectively. Chemical modification indicated that sulfhydryl groups are probably not essential for activity while carboxyl groups may be involved in the active site of the enzyme.

Production of Fructose Rich Syrups Using Invertase From Date Palm Fruits

“…Catalytic efficiency is 2.05 mM/µmol/min/mL. These values, as well as the effect of temperature and pH, were in accordance with those founded in other higher plant invertases (Al‐Bakir and Whitaker 1978; Karuppiah et al . 1989; Lee and Sturm 1996; Tang et al .…”

“…These preparations were stable with a pH varying from 3 to 7. This behavior toward temperature and pH was similar to the result of Al‐Bakir and Whitaker (1978) on the Zahdi variety. It is the only work that has focused on the characterization and purification of invertase from dates.…”

Changes in Soluble Sugar Content During the Development of Fruits in Some Varieties of Omani Date Palm (Phoenix dactylifera)

“…Omani dates are generally smaller than dates from elsewhere in the Arabian Peninsula and contain the reducing sugar fructose as their major detectable component, while Saudi dates contained high levels of the non-reducing sugar sucrose. The absence of sucrose in Omani dates can be attributed to the high, and usually continuous, activity of the enzyme invertase, which splits the disaccharide sucrose to its constituent monosaccharides (Rygg, 1975;Al-Bakir and Whitaker, 1978). Our findings are in agreement with these results.…”

Effect of Acid Whey, Enzymatic Whey, Magnetized and Unmagnetized Whey on the Qualitative and Productive Traits of Date Palm

“…Then, the mixture was filtered through a filter paper and wash the precipitate Remaining again using 25 mL of the same extraction solution and filtered through filter paper, mix the washed precipitate with extraction solution (2) at the same extraction rate, and filter the mixture as in the method above, and use the filtrate (enzyme solution) to estimate the effectiveness of the enzyme invertase only. The Andrology method (Al-Bakir & Whitaker, 1978).…”