Purification and Characterization of Alkaline-Thermostable Protease Enzyme from Pitaya (Hylocereus polyrhizus) Waste: A Potential Low Cost of the Enzyme

Table 2

Effect of metal ions, inhibitors, organic solvent, and surfactant and oxidizing agents on the protease activity.

Type	Agent	Concentration	Relative activity
	Noncomponents	—	100 ± 0.0^a
Metal ions	Li^+	10%	100 ± 0.1^a
	K^+	10%	100 ± 1.2^a
	Na^+	10%	100 ± 1.1^a
	Sn^2+	10%	100 ± 1.0^a
	Ca^2+	10%	125 ± 0.2^b
	Mg^2+	10%	110 ± 1.1^ab
	Cu^2+	10%	105 ± 0.5^ab
	Fe^2+	10%	52 ± 0.01^c
	Zn^2+	10%	38 ± 0.3^d
Inhibitors	EDTA	10 mM	115 ± 0.3^ab
	Ovomucoid	10 mM	100 ± 0.1^a
	-Mercaptoethanol	10 mM	100 ± 0.2^a
	Iodoacetic acid	10 mM	100 ± 0.3^a
	Bestatin	10 mM	100 ± 1.1^a
	DTNB	10 mM	82 ± 0.0^ab
	PMSF	10 mM	0.0 ± 1.1^e
Organic solvent	Acetate	10%	100 ± 0.3^a
	Ethanol	10%	100 ± 0.3^a
	Isopropanol	10%	92 ± 0.2^d
	Methanol	10%	83 ± 1.1^d
Surfactant and oxidizing agents	Triton X-100	5%	100 ± 1.1^a
	Tween-80	5%	100 ± 0.3^a
	SDS	5%	73 ± 2.1^f
	H2O2	2 M	62 ± 0.2^g

The residual protease activity was determined after incubation of the enzyme with various phase components at room temperature for 1 h. The sample size for all experiments was three. Mean value followed by different letters differs significantly .