Effects of some drugs on human erythrocyte 6-phosphogluconate dehydrogenase: an in vitro study

Figures & data

Figure 1.  SDS-PAGE bands of 6PGD. Lane 1, human erythrocyte glutathione reductase; lane 2, standards: bovine erythrocyte carbonic anhydrase-I (29 kDa), chicken ovalbumin (45,000), bovine albumin (66,000); lane 3, human erythrocyte glucose 6-phosphate dehydrogenase; lane 4, human erythrocyte 6PGD.

Figure 2.  Activity % vs. [Ketotifen] regression analysis graph for human erythrocyte 6PGD in the presence of five different ketotifen concentrations.

Table 1.  Purification scheme of 6-phosphogluconate dehydrogenase from human erythrocytes.

Purification step	Total volume (mL)	Activity (U/mL)	Total activity (U)	Protein (mg/mL)	Specific activity (U/mg)	Yield (%)	Purification factor
Hemolysate	60	0.120	7.2	30.88	0.0039	100	1
Ammonium sulfate precipitation (35–65%)	20	0.305	6.1	32.12	0.0090	84.72	2.3
2′,5′-ADP Sepharose 4B affinity chromatography	8	0.525	4.2	0.04	13.1200	58.33	3364

Table 2.  K_i values obtained from Lineweaver–Burk graphs for 6PGD in the presence of three fixed inhibitors and five substrate concentrations for different drugs.

Drug	IC50 (mM)	Ki	Inhibition type
Ketotifen	0.0084	8.3 ± 1.7 μM	Non-competitive
Dacarbazine	0.0120	10.1 ± 0.7 μM	Non-competitive
Meloxicam	0.0550	50.9 ± 13.2 μM	Non-competitive
Furosemide	0.1250	127 ± 37.8 μM	Non-competitive
Methotrexate	0.1420	136.7 ± 25.3 μM	Non-competitive
Metochloropramide hydrochloride	3.2700	2.1113 ± 0.6979 mM	Non-competitive
Ritodrine hydrochloride	3.6600	6.0353 ± 1.2783 mM	Non-competitive
Gadopentetic acid	209.10	73.4 ± 21.9 mM	Non-competitive

Figure 3.  Lineweaver–Burk graph for five different substrate (6-PGA) concentrations and three different ketotifen concentrations for determination of K_i.