Irreversible inactivation of yeast glucose-6-P dehydrogenase by penicillin G

Summary Yeast glucose-6-P dehydrogenase is irreversibly inactivated by penicillin G. Kinetic data show that 1 molecule of penicillin G reacts with each active unit when the enzyme is inactivated The rate of inactivation increases greatly with increasing pH. This irreversible inactivation by penicillin G is largely prevented by pyridoxal-P, a reversible inactivator of this enzyme. Prior treatment of penicillin G with penicillinase totally abolishes its ability to inactivate the enzyme.This work was supported by grant RR-8006 from the General Research Branch, Division of Research Resouces, NIH (USA).     

Reactivation of yeast glucose-6-phosphate dehydrogenase denaturated by saturated fatty acids

Summary Activity of yeast glucose-6-phosphate dehydrogenase, inactivated by treatment with saturated fatty acids, can be partially restored by incubation in a medium of suitable ionic composition. The effectiveness of ions in the reactivation process is inversely related to their chaotropic properties. Time-dependence of reactivation extent suggests a 2-step mechanism of enzyme inactivation and the existence of an intermediate form that aggregates through a 2nd-order reaction, producing irreversibly inactive enzyme.This work was supported by a grant of the Italian Consiglio Nazionale delle Ricerche.     

Tumour glucose-6-phosphate dehydrogenase inhibition by actinomycin

Zusammenfassung Die Aktivität der Glukose-6-phosphat-Dehydrogenase (G-6-PD) wurde in Extrakten des heterotransplantierten Humantumors GW-39 nach cytostatischer Therapie mit Actinomycin C untersucht. Es kam zu einer signifikanten Hemmung der G-6-PD-Aktivität in den Tumoren, während die Enzymaktivität in der Leber der tumortragenden Wirtstiere (Hamster) unbeeinflusst blieb. Diese Ergebnisse entsprechen unseren, an einem histopathologisch ähnlichen Humantumorsystem (H.Ad. No. 1) früher erhobenen Befunden und bestätigen damit den tumorspezifischen Enzymeffekt der Behandlung mit Actinomycin C.

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This work was supported in part by a grant from the Deutsche Forschungsgemeinschaft.     

Erythrocyte glucose-6-phosphate dehydrogenase deficiency and thalassemia

Résumé L'activité de la glucose-6-phosphate déhydrogènase était normale dans les érythrocytes obtenus de sujets atteints de Thalassémie (majeure ou mineure) d'Hémoglobine E - Thalassémie et dans des érythrocytes contenant une variété d'hémoglobines anormales. Chez trois des six sujets atteints d'Hémoglobine H - Thalassémie, la glucose-6-phosphate déhydrogènase était absente.     

Quantitative distribution of glucose-6-phosphate dehydrogenase and isocitric dehydrogenase in the human nephron

Zusammenfassung In den einzelnen Abschnitten des menschlichen Nephrons und in Nierenhomogenaten wurden quantitativ die Glucose-6-phosphat-dehydrogenase-und die Isozitronens?uredehydrogenase-Aktivit?t gemessen.

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This investigation was made possible by a grant from the Swiss National Foundation for the Development of Scientific Research. The technical assistance of MissD. Keller is gratefully acknowledged.     

The incidence of erythrocyte glucose-6-phosphate dehydrogenase deficiency in Singapore

Résumé Chez des anémiques de sexe masculin étudiés à Singapour, l'auteur a constaté l'absence ou la déficience de l'activité de la glucose-6-phosphate déhydrogénase érythrocytaire dans les proportions suivantes: 2,5% sur 240 Chinois, 3,33% sur 132 Indiens, 37,5% sur 16 Israélites et 0,65% sur 155 Malais. L'absence de cette activité enzymatique était fréquente chez les malades chinois, malais et israélites hospitalisés pour anémie grave, ictére grave des nouveau-nés, anémie hémolytique ou hémoglobinurie.

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Acknowledgements. The work reported here was carried out while the author was a Lecturer in the Department of Biochemistry, University of Malaya in Singapore.I am grateful to ProfessorA. G. Motulsky and Dr.J. M. Campbell of the Department of Medicine, University of Washington, Seattle (Washington), for making available to me details of their method for the rapid detection of glucose-6-phosphate dehydrogenase activity in erythrocytes, to Mr.S. Pang for valuable technical assistance, and to all those who have helped me in collection of the samples referred to in this report.     

Inactivation of human glutamate dehydrogenase by aluminum

Aluminum inactivated glutamate dehydrogenase (GDH) by a pseudo-first-order reaction at micromolar concentrations. A double-reciprocal plot gave a straight line with a k_inact of 2.7 min^-1 and indicated the presence of a binding step prior to inactivation. The inactivation was strictly pH dependent and a marked increase in sensitivity to aluminum was observed as the pH decreased. At a pH higher than 8.5, no inactivation was observed. The completely inactivated GDH contained 2 mol of aluminum per mole of enzyme subunit monomer. When preincubated with enzyme, several chelators such as citrate, NaF, N-(2-hydroxyethyl) ethylenediaminetriacetic acid or ethylenediaminetriacetic acid efficiently protected the enzyme against the aluminum inactivation. In a related experiment, only citrate and NaF released the aluminum from the completely inactivated aluminum-enzyme complex and fully recovered the enzyme activity. Ferritin, NADP⁺, or nerve growth factor did not show any effects on the recovery of the aluminum-inactivated GDH activity. The dissociation constant for the aluminum-enzyme complex was calculated to be 5.3 M. Although aluminum has been known to form a complex with nucleotides, no such effects were observed in the inactivation of GDH by aluminum as determined using GDHs mutated at the ADP-binding site, NAD⁺-binding site or GTP-binding site. Circular dichroism studies showed that the binding of aluminum to the enzyme induced a decrease in helices and sheets and an increase in random coil. Therefore, inactivation of GDH by aluminum is suggested to be due to the conformational change induced by aluminum binding. These results suggest a possibility that aluminum-induced alterations in enzymes of the glutamate system may be one of the causes of aluminum-induced neurotoxicity.Received 25 July 2003; received after revision 27 August 2003; accepted 15 September 2003     

Inhibition of human testicular glucose-6-phosphate dehydrogenase by unsaturated C19-steroids

Zusammenfassung Die Bebrütung einer gereinigten G-6-PDH aus menschlichem Testisgewebe mit 3-substituierten ⁴- oder ⁵-C₁₉-Steroiden zeigte, dass 3-Hydroxy-⁴-oder ⁵-androsten-17-on auch wirksame Inhibitoren der testikulären G-6-PDH darstellen. Zur gleichen Zeit konnten die früher gefundenen Zusammenhänge zwischen chemischer Struktur eines Steroids und seiner biologischen Aktivität im G-6-PDH-Hemmtest uneingeschränkt bestätigt werden.     

Studies on glucose-6-phosphate dehydrogenase: Variability in ATP inhibition

Zusammenfassung Es wird eine Glukose-6-Phosphat-Dehydrogenase in Erythrozyten des Menschen beschrieben, bei der die Michaelis-Konstante für Glukose-6-Phosphat und die Inhibitor-Konstante für Adenosintriphosphat erniedrigt sind. Erythrozyten des Schafes zeigen keine kompetitive Hemmung mit ATP.

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Contribution No. 150, Department of Pathology, College of Veterinary Medicine, Kansas Agricultural Experiment Station, Manhattan, 66502.

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This investigation was supported in part by USPHS grant No. HE 12972 and the Kansas Agricultural Experiment Station.     

Hybridization studies in the further characterization of erythrocyte glucose-6-phosphate dehydrogenase

Zusammenfassung Die Hybridisierung von Ratten- und Rinder-Glukose-6-Phosphat Dehydrogenase ergibt 2 Hybride, was darauf hindeutet, dass das Enzym in beiden Gattungen ein Polymer von verschiedenen Aminosäureketten ist.     

Studies on haemoglobin variants and glucose-6-phosphate dehydrogenase in Indian sheep and goats

Résumé Deux variantes d'hémoglobine Hb-A et Hb-B ont été démontrées chez le bouc et le mouton Indiens. Les fréquences génétiques pour Hb-A et Hb-B sont respectivement 0.135 et 0.865.Le fervent déhydrogénase de glucose-6-phosphate chez les érythrocytes de bouc et de mouton est absent. Nous avons employé la méthode semi-quantitative deMoutulsky pour la détermination de l'activité de déhydrogénase de glucose-6-phosphate.     

The activity of erythrocyte glucose-6-phosphate dehydrogenase as an indicator of the rate of erythropoiesis

Zusammenfassung Bei 29 Patienten mit verschiedenen hämatologischen Affektionen wurde eine positive Korrelation zwischen Glucose-6-phosphatdehydrogenase-Aktivität der Erythrozyten und dem Erythrozyten-Eisenumsatz gefunden.     

Semiquantitative assay of erythrocyte glucose-6-phosphate dehydrogenase activity by a new modification of theMotulsky test

Zusammenfassung Es wird eine weiter vereinfachte Variante des vonMotulsky angegebenen Farbstofftests beschrieben, die keine besonderen Laboratoriumseinrichtungen erfordert und für klinische Zwecke ausreichend genaue semiquantitative Resultate ergibt.     

Coupling of fructose-1,6-P2 to aminated agarose by Schiff base reduction. Affinity chromatography of yeast aldolase

Summary Fructose-1,6-P₂ was immobilized by sodium borohydride reduction of the Schiff base formed with aminated agarose (AH-Sepharose 4B^®). The coupling occurs with high yield (25 moles immobilized fructose-1,6-P₂ per ml packed gel) at neutral pH and room temperature. Schiff base reduction thus provides a convenient and mild coupling procedure for sugar phosphates preserving their labile phospho ester bonds. As exemplified by a new isolation procedure for fructose-1,6-P₂ aldolase from yeast, sugar phosphates insolubilized in this manner may be used for affinity chromatography of the corresponding enzymes, provided that contaminating unspecific phosphatases are removed in a preceding fractionation step.This work was supported by the Swiss National Science Foundation, grant No. 3.620-0.75. A preliminary account has been presented at the 10th Int. Congress of Biochemistry, Hamburg, 1976, Abstracts. p. 194.Acknowledgment. The excellent technical assistance of Alice Gasser is gratefully acknowledged