Erythrocyte glucose-6-phosphate dehydrogenase from Brazilian opossum Didelphis marsupialis
Braz. j. med. biol. res
;
39(5): 611-614, May 2006. ilus, tab
Article
in English
| LILACS
| ID: lil-425795
RESUMO
In a comparative study of erythrocyte metabolism of vertebrates, the specific activity of glucose-6-phosphate dehydrogenase (G6PD) of the Brazilian opossum Didelphis marsupialis in a hemolysate was shown to be high, 207 ± 38 IU g-1 Hb-1 min-1 at 37°C, compared to the human erythrocyte activity of 12 ± 2 IU g-1 Hb-1 min-1 at 37°C. The apparent high specific activity of the mixture led us to investigate the physicochemical properties of the opossum enzyme. We report that reduced glutathione (GSH) in the erythrocytes was only 50 percent higher than in human erythrocytes, a value lower than expected from the high G6PD activity since GSH is maintained in a reduced state by G6PD activity. The molecular mass, determined by G-200 Sephadex column chromatography at pH 8.0, was 265 kDa, which is essentially the same as that of human G6PD (260 kDa). The Michaelis-Menten constants (Km 55 æM) for glucose-6-phosphate and nicotinamide adenine dinucleotide phosphate (Km 3.3 æM) were similar to those of the human enzyme (Km 50-70 and Km 2.9-4.4, respectively). A 450-fold purification of the opossum enzyme was achieved and the specific activity of the purified enzyme, 90 IU/mg protein, was actually lower than the 150 IU/mg protein observed for human G6PD. We conclude that G6PD after purification from the hemolysate of D. marsupialis does not have a high specific activity. Thus, it is quite probable that the red cell hyperactivity reported may be explained by increased synthesis of G6PD molecules per unit of hemoglobin or to reduced inactivation in the RBC hemolysate.
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Index:
LILACS (Americas)
Main subject:
Didelphis
/
Erythrocytes
/
Glucosephosphate Dehydrogenase
/
Glutathione
Limits:
Animals
Country/Region as subject:
South America
/
Brazil
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2006
Type:
Article
Affiliation country:
Brazil
Institution/Affiliation country:
Fundação Parque Zoológico de São Paulo/BR
/
Instituto Adolfo Lutz/BR
/
Universidade Federal do Maranhão/BR
/
Universidade de São Paulo/BR
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