Studies on the binding of copper to dopamine beta-monooxygenase and other proteins using the Cu2+ ion-selective electrode.
The binding of Cu2+ to native and copper-free dopamine beta-monooxygenase has been investigated by potentiometric titrations using a Cu2+-selective electrode. Stoichiometric formation constants have been determined from regression analysis of the resulting titration curves. The results establish a stoichiometry of four high-affinity binding sites for Cu/+ (log Kf approximately 11) per enzyme tetramer, and more binding sites of lower affinity (log Kf approximately 5-7). The data for binding of the first four Cu2+ to the enzyme tetramer indicate interactions in the binding to the sites. Bovine serum albumin, metal-free carbonic anhydrase, and ovotransferrin have also been titrated with Cu2+, and the formation constants of both high-affinity binding sites and other sites have been determined. The stoichiometry of one high-affinity binding site of Cu2+ for carbonic anhydrase (log Kf approximately 10-12) and two sites for ovotransferrin (log Kf approximately 11) agree with the reported metal binding properties of these proteins. The number of high-affinity binding sites for bovine serum albumin was pH dependent.
Syvertsen
C
C
Gaustad
R
R
Schrøder
K
K
Ljones
T
T
D000313:Adrenal Medulla / Q000201:enzymology; D000818:Animals; D002256:Carbonic Anhydrases / Q000378:metabolism; D002417:Cattle; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003207:Conalbumin / Q000378:metabolism; D003300:Copper / Q000032:analysis / Q000378:metabolism*; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism*; D004566:Electrodes; D011199:Potentiometry; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000032:analysis
D003207:Conalbumin; D012710:Serum Albumin, Bovine; D003300:Copper; D004299:Dopamine beta-Hydroxylase; D002256:Carbonic Anhydrases