Abstract
1. The presence of an inorganic pyrophosphatase (PPi-ase) with a pH optimum of 8.7, could be demonstrated in the molars of 3-day old hamsters, where it was primarily located in the sedimentable fraction. 2. No significant acid PPi-ase activity could be detected either in the supernatant or in the sedimentable fraction. 3. Zn2+, and possibly Co2+, appears to act as a cofactor for the PPi-ase activity; Mg2+ increases the PPi-ase activity, probably because Mg-PP 2−i is the true substrate for the enzyme.
Résumé
1. La présence de pyrophosphatase inorganique (PPi-ase), à pH optimum de 8.7, a pu être mise en évidence au niveau des molaires de hamsters, âgés de 3 jours. L'activité se situe dans la fraction qui précipite. 2. Aucune activité en PPi-ase acide n'est observée dans le surnageant ou la fraction qui précipite. 3. Zn2+, et possiblement le Co2+, semblent agir comme co-facteur pour l'activité de la PPi-ase. Mg2+ augmente l'activité en PPi-ase, car Mg-PP 2−i est sans doute le vrai substrat de l'enzyme.
Zusammenfassung
1. Die Anwesenheit von anorganischer Pyrophosphatase (PPi-ase) mit einem pH-Optimum von 8.7 konnte in den Molaren von 3 Tage alten Hamstern gezeigt werden; das Enzym wurde vorwiegend in der ausfällbaren Fraktion gefunden. 2. Weder im Überstand noch in der ausfällbaren Fraktion konnte eine signifikante saure PPi-ase-Aktivität nachgewiesen werden. 3. Zn2+ und möglich Co2+ scheinen als Cofaktoren für die PPi-ase-Aktivität zu wirken; diese wird durch Mg2+ erhöht, vermutlich weil Mg-PP 2−i das eigentliche Substrat für das Enzym ist.
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