On the acrylamide disc electrophoresis pattern of human G6PD

Crosti, N.; Cagiano-Malvezzi, D.

doi:10.1007/bf00485996

Cited by 6 publications

(2 citation statements)

References 7 publications

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“…Such oxidation-reduction reactions of cysteine residues have been implicated in generating the three-band pattern observed on polyacrylamide gel electrophoresis of G6PD from human erythrocytes and other tissues (88,374) and rat liver (375); similar results with rat mammary GGPD ( 15 1,152) are described above.…”

Section: Polymers Of a Single Subunit And Conformational Isomerssupporting

confidence: 65%

Glucose‐6‐Phosphate Dehydrogenases

1979

Advances in Enzymology - And Related Areas of Molecular Biology

104

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Section: Polymers Of a Single Subunit And Conformational Isomerssupporting

confidence: 65%

Glucose‐6‐Phosphate Dehydrogenases

1979

Advances in Enzymology - And Related Areas of Molecular Biology

104

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“…Different dissociated enzyme forms appear to aggregate to form the active enzyme. NADP was earlier found to have a similar substrate effect in the case of glucose-6-phosphate dehydrogenase [29,30]. This effect is also responsible for the homogeneity of the purified enzyme.…”

Section: Discussionmentioning

confidence: 82%

Evidence against the Existence of Real Isozymes of Hypoxanthine Phosphoribosyltransferase

1978

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A method for reducing the degree of heterogeneity in the electrophoretic enzyme activity pattern of hypoxanthine phosphoribosyltransferase preparations by incubation with a (magnesium) phosphoribosyl diphosphate substrate is described. Hypoxanthine phosphoribosyltransferase was isolated from human erythrocytes and Chinese hamster livers. A subunit molecular weight of 26 000–27 000 as reported by other authors was obtained for both enzymes by gel electrophoresis in the presence of dodecylsulfate. Gradient gel electrophoresis revealed that the native enzymes mainly have a molecular weight of 105 000–110 000 and are thus apparently tetrameric, when held in the active state by the presence of phosphoribosyl diphosphate. The dimeric enzyme with a molecular weight of 52 000–55 000, was also found under other conditions. The trimer occurred only in the absence of phosphoribosyl diphosphate, for instance by glycerol gradient centrifugation. The enzyme from human erythrocytes was partly degraded during purification in the absence of a protease inhibitor. The purified enzyme has a very low protease contamination level. Proteolysis is an additional cause of heterogeneity and might therefore explain earlier conflicting results. Since the heterogeneous nature of hypoxanthine phosphoribosyltransferase is caused only by the secondary processes of dissociation/association and, in the case of the human erythrocyte enzyme, degradation, we suggest that the use of the term ‘isozyme’ to describe the different forms should be avoided.

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Relationship of heat labile glucose‐6‐phosphate dehydrogenase and multiple molecular forms of the enzyme in senescent human fibroblasts

Duncan

Dell’Orco

Guthrie

1977

Journal Cellular Physiology

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Human fibroblasts derived from newborn foreskin and designated CF-3 were assayed for heat labile glucose-6-phosphate dehydrogenase (G6PD) when they had grown to confluency, as well as when they were arrested in an essentially nonmitotic state. Under both culture conditions there was an increase in heat labile G6PD (up to 25% of the total activity) as cells progressed through their in vitro lifespan; however, arrested cells exhibited less heat labile G6PD than did comparable growth controls (5-10% decrease). Acrylamide gel electrophoresis of crude G6PD preparations revealed three distinct bands of enzymatic activity. One of the bands was tentatively identified as the dimeric form of the enzyme and another as the tetrameric form. The tetrameric form was more heat sensitive, and the percent of the total activity of this form increased as the cells became senescent. The percent of total activity of the tetrameric form was comparable to the percent heat labile enzyme assayed at a given population doubling level. These results indicated that the observed increase in heat lability of G6PD with age may be due to a shift in equilibrium to the tetrameric form of the enzyme rather than the synthesis of aberrant enzyme molecules.

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On the acrylamide disc electrophoresis pattern of human G6PD

Cited by 6 publications

References 7 publications

Glucose‐6‐Phosphate Dehydrogenases

Glucose‐6‐Phosphate Dehydrogenases

Evidence against the Existence of Real Isozymes of Hypoxanthine Phosphoribosyltransferase

Relationship of heat labile glucose‐6‐phosphate dehydrogenase and multiple molecular forms of the enzyme in senescent human fibroblasts

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