Interactions of melatonin and serotonin with lactoperoxidase enzyme

Figures & data

Table 1.  Purification scheme of lactoperoxidase obtained after the application of different purification steps.

Purification step	Total volume (mL)	Enzyme activity (EU/mL)	Total enzyme activity (ABTS unit)	Protein (mg/mL)	Total protein (mg)	Specific activity (EU/mg)	Activity yield (%)	Purification-fold
Homogenate	180	3.83	689	1.65	297	2.3	100	1.00
Ammonium sulfate precipitation	32	16.30	522	1.88	60.2	8.7	75.8	3.7
CM-Sephadex C-50 column chromatography	275	1.72	473	0.1	27.5	17.2	68.7	7.4
Ammonium sulfate precipitation	30	13.52	407	0.72	21.6	18.8	59.1	8.1
Sephadex G-100 column chromatography	160	2.06	330	0.07	11.2	29.43	47.9	12.7
Ammonium sulfate precipitation and dialysis	23	6.48	149	0.19	6.21	34.0	21.6	14.7

Figure 1.  Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) bands of lactoperoxidase (LPO) purified from bovine milk. Column a: standard proteins, 1: maltose-binding protein (MBP)–β-galactosidase (fusion of MBP and β-galactosidase, 175 kDa); 2: MBP–paramyosin (fusion of MBP and paramyosin, 80 kDa); 3: MBP–chitin binding domain (CBD) (fusion of MBP and CBD, 58 kDa); 4: CBD–Mxe Intein–2CBD (fusion of CBD and Mxe Intein followed by two CBDs, 46 kDa). Column b: purified LPO from bovine milk.

Figure 2.  The effect of different concentrations of melatonin (0.5–2.5 mM) on lactoperoxidase obtained from bovine milk.

Figure 3.  Lineweaver–Burk plot for different ABTS concentrations and three different melatonin concentrations for determination of K_i constant.

Figure 4.  The effect of serotonin at different concentrations (0.5–2.15 mM) on bovine milk lactoperoxidase.

Figure 5.  Lineweaver–Burk plot for different ABTS concentrations and three different serotonin concentrations for determination of K_i constant.