Noncovalent Immobilization of Pectinesterase (Prunusarmeniaca L.) onto Bentonite

Figures & data

Table 1. Chemical composition of bentonite

Compound	Amount (%)
SiO2	70±2.0
Al2O3	14±1.0
Fe2O3	1.8±0.2
CaO	0.7±0.2
MgO	1.7±0.2
K2O	1.8±0.2
Na2O	0.4±0.2

Table 2. Purification of pectinesterase enzyme isolated from Malatya apricot

Purification Step	Volume (mL)	Total activity (unit)	Total Protein (mg)	Specific Activity (unit/mg protein)	Yield%	Purification n-fold
Crude extract	1060	1742.6	298.9	5.83	100	1.0
80% (NH4)2SO4 precipitation	125.5	880.76	29.1	30.27	50.5	5.2
Dialysis	122.5	1666.7	23.5	70.92	95.6	12.2

Table 3. Immobilization of PE from Malatya apricot on bentonite

Free enzyme		Immobilized enzyme
Protein (mg/2.15 g bentonite) (x)	Specific activity (unit/mg)	Protein in washing (mg) (y)	Bound protein (mg) (x-y = A)	Activity (unit)	Specific activity (unit/mg)	Activity yield (%) (A/x.100)
1.44	5.83	0,141	1,299	11.428	9,298	90,2

Figure 1.  Effect of pH on the activity of free and bentonite-immobilized apricot PE.

Figure 2.  Optimum temperature of free and immobilized Malatya apricot PE enzyme.

Figure 3.  The thermal stability profile for bentonite-immobilized apricot PE.

Figure 4.  The thermal stability profile for free apricot PE.

Figure 5.  Arrhenius plot for heat inactivation of bentonite-immobilized apricot PE.

Table 4. Inactivation rate constant and half-lives (t_1/2) of free and immobilized apricot PE

	Inactivation rate constant, k(×10^3)(min^−1)		t1/2 (ln 2/ k) (min)
Temperature (°C)	Free enzyme	Immobilized enzyme	Free enzyme	Immobilized enzyme
70	2.55	1.55	290	440
80	2.63	1.82	260	380
90	3.007	2.35	230	300

Figure 6.  Lineweaver-Burk plots of apricot PE activity as a function of substrate concentration. Reaction mixtures contained varying levels of pectin (0.05–1 mM) in 0.1M NaCl (w/v) and 0.4 ml of partially purified enzyme. The pH of the reaction was 9.0 and the temperature was 30°C.

Figure 7.  Lineweaver-Burk plots of bentonite-immobilized Malatya apricot PE activity as a function of substrate concentration. Reaction mixtures contained varying levels of pectin (0.05–1 mM) in 0.1M NaCl (w/v) and 0.05 g of patially purified enzyme. The pH of the reaction was 9.0 and the temperature was 30°C.

Figure 8.  Storage stability of free and immobilized PE from Malatya apricot pulp at 4°C.